Please help!!! Payday loan company calls everyday!!! :(

Hi.. i hope someone can help me. I live in Michigan and have a payday loan that I defaulted in from a local Advance America cash advance location. They tried to deposit the original check I wrote which was for $676.45 ($600 loan amount plus interest). But there were insufficient funds in my account so the electronic withdraw they tried to make with my check was returned to them unpaid due to insufficient funds. I was already in a repayment agreement with them, but couldnt even make the 1st payment back of the $676.45 total. Now since my check was returned to them as unpaid, they call everyday and I havent accepted their calls but theyve been leaving voicemails to call them saying its imperative that I return their calls etc.
I want all their phone calls to stop!! Can I send them a letter stating to only contact me via mail not by phone? I thought there was something in the Fair Debt Collections Practices Act (FDCPA) or something that states they would have to stop contacting me via phone if I send them a letter? I'm not sure if it varies based on the state I live in or what.
I will be able to pay them like $100 every 2 weeks until its paid off, but i know if I talk to them they'll demand more. I just wish I could write them a letter and send them a $100 payment in certified funds and let them know i'll be sending them certified payments every 2weeks. Do you think doing all of this would make them stop calling me? I dont mind if they send me things in the mail but I do not want them calling me, my work, family (references I listed on application) etc. If so, is there a sample letter you would recommend? Please help.. I'd really appreciate it as I want to type up, sign , and send the letter asap!!! Thanks so much in advance.

Unfortunately if you dont answer their calls they can and will continue until they send it to collections. My experience with Advance America was quite easy getting them to do a workout plan though.

FDCPA does not apply to your original lender (Advance America). It applies to third party collectors.

You need to call these people and set up a payment arrangement. They won't go away and they will continue to add fees and interest to your account.

AA is generally easy to work with regarding setting up an extended payoff plan. Since you've already defaulted on one, they may not be as friendly with you this time, but you need to call and get this taken care of.