2 Companies collecting on same loan?

I had a couple of student loans on deferment when I became injured and was unable to work. Lots of medical stuff going on and I just did not keep up on this issue. That it went into default is entirely my fault, I am not attempting to get out of paying nor shift the blame elsewhere. That being said, here's what has gone on over the past 30 some odd days.

Last month I got a letter stating my loans had been placed collections and if I did not respond to the letter they were going to pursue having my wages garnished. I promptly called the number on the letter to find out what was going on and why I was just now hearing of this, I had gotten no letters prior to this one. Turns out the letters were being sent to the wrong address.

Anyway, because I knew I owed on student loans I went ahead and set up a payment plan with the lady on the phone. She wanted 3 reference phone numbers (is that normal?) which I promptly gave. I was to do 12 payments in 12 months, the first would come out of my bank account that day. I gave her my bank account info and she said I would receive an email about the payment plan and receive regular mail, at the corrected address.

A couple of weeks passed and I got a call from her stating there was an issue with my check. She said the check had not gone through because the bank said it was not a valid account number. I had her read back the number to me and it was the same as the numbers on the checkbook in my hand. I told her I would call my bank on Monday and see what was going on. I called the bank, they said the number was correct and they had no idea why she was being told it was not a valid account number.

Then things began to get crazy. When I told her what the bank had said, she became rude. I think she believed I was trying to get out of making the payments. At this point, I thought it best to stop communicating with her via phone. I told her I had never received the email she said I would get or the paper documents. I asked her to please send documents verifying that her company holds the student loan, the amount owed, the payment plan, and an address to send a certified check via certified mail. She refused to send me any documentation. I told her that things were getting fishy and unless I could verify who I was sending money to and for what, I would not be paying. I thanked her for her time and hung up.

I began getting calls from her 4-5 times a day, the very next day. One of the people she took as a reference phone number began getting calls. I called them back and repeated my request for verification. They were not interested in verifying but they did say that two of the phone numbers I gave them were coming back as wrong area code. I am starting to suspect they have some issues entering numbers into their system. I told her the numbers were very much correct to which she asked if I was calling to make a payment.

Yesterday I called the Us Dept of Education to find out what was going on, this should have been my first step. Live and learn. I was indeed in default, letters were sent to an old address. I updated my address with them. Since I did not have the money owed, $5,000, I would have to work with the collections place. I asked for the name, she said CBE. This was not the name of the first place, Pioneer Credit Recovery. I told her about the different company. She gave me a number to call and told me to tell them about the trouble I had had with Pioneer Credit Recovery. I called CBE, was transferred to some dept within CBE. I told the guy who answered what was going on. He stated they held the loan, quoted the same amount that the Us Dept of Ed did. I set up a repayment plan, if I pay for 9 months it gets kicked back to the Dept of Ed and off my credit report. While on the phone with him, setting up this plan, Pioneer Credit was calling me. I let it go to voicemail. The payment amount with CBE was for $50 a month for 9 months. He said I would receive a billing statement in the mail. He also took reference phone numbers, but 2 instead of 3.

When I got off the phone with him, I called Pioneer. When I identified myself to the lady who answered, her first comment was "Are you calling to pay?" I let her know what Us Dept of Ed had said and about CBE. She told me that it was not possible that I had paid $50 on the loan since I had not paid it to her company and that the bank account number I had given them had resulted in a bounced payment. I told her I had indeed paid $50 and that I had sat on the phone with the man while he entered the acct number into the computer and it had been accepted, unlike with her company. She told me I still owed her company money and that I must have paid on some other loan. I asked her for the amount, loan number, etc. Her amount was different than what the Us Dept of Ed quoted me. She then said that it was different (higher) because of interest rates her company had applied. I asked for the amount without the interest rates. This number came out to the same number Us Dept of Ed and CBE gave me. She then stated that it had to be a totally different loan because her loan was not through the Us Dept of Ed but through NW Education Loan and Wells Fargo. She stated I must have gotten multiple loans without knowing it. That a school year is 3 semesters (if you count summer), I went for 2 years, that's 6 loans. I told her my uni goes by quarters, not semesters, and there are 4 quarters in a year, so I went for 8 quarters and I know I did not have 8 loans. This resulted in her arguing over how 4 quarters x 2 years = 4 loans until I cut her off. I told her I needed to sort it all out, though I'm not sure how to do so. She told me to call the other company, get as much info from them as I can, and fax her whatever they give me. I told her I would work on figuring out what was going on and call her back Monday.

Now I haven't the slightest idea who I should be paying, how much, or for how long. I went to the nslds site and I have 4 loans. Each one says disbursed, defaulted, and a date. None of them say anything about Pioneer or CBE.

1. Direct Stafford Unsubsidized = $657
2. Direct Stafford Subsidized = $1,805
3. Stafford Subsidized = $1,580
4. Stafford Subsidized = $2,705

How can two companies hold the same loan? Can I request that they send me verification that they hold the debt? If they wont send verification what do I do? Can I request communication via mail and not phone for these Pioneer people? If they are the ones who hold the debt, I am fine paying since I owe the money, I am not contesting that. I'm just trying to figure out WHO I have to pay it to and if it is them, after their... inability to get my information correct and lack of tact, I'd rather a) deal with them via paper and not person to person b) be certain I have a paper trail in case they goof up again and accidentally delete every payment I make or something.