International Asset Group Question

I got a call from International Asset Group and they stated that I owed $1,200.00 for a payday loan that I took out in in 2006 that was $535.00. They stated that if I payed them by the end of the month that they would take $625.00 as a settlement. The lady Ms. Carter was very rude and told me that they were suing me for check fraud and attempting to defraud a federal bank. Now I know they "hot check law" in Texas and I know that the burden of proof is on the prosecution, and that there is no way to prove that someone intentionally meant to not have the funds in their account for the post dated check. I took this payday loan out online and just haven't had the money to pay it back due to other debts and being in school. She continued to say that she would put a 48 hour hold on the account and that I could call back with a decision. I called back and spoke with a Mr. Jeff Crain and he was suppose to send me a DV debt verification letter via email, but he never did. A process server called me today and stated that he was suppose to come and serve me papers today, and all he would give me was the number to IAG and my case number. I called them and spoke with Ms. Carter again and again she was very rude and I ended up talking to another man, not sure of his name, and he said they could settle it for $500.00 if I paid today or tomorrow, but if not they would still do the $625.00 by the end of the month, and that he would put a 24 hour hold on the account so I could make a decision. Now, I now that this whole time they have been breaking FTC laws and various law under Texas Statute, Finance Code, Title 5, Chapter 392. Im not aware of all of the legal aspects, I just did a little research. I do not dispute the fact that I owe for the payday loan, and I want to pay it, I just don't have the means to do it by the end of the month. My question is what should I do about this to buy myself some time, maybe about two more weeks and then I can take the $500.00 settlement amount. Also I was reading somewhere else that it is not wise to send the money via moneygram, that I should send a moneyorder certified mail to them, is this true? I know that they close their books at the end of the month, which is why they are so adament about trying to get their money. Also I called back and asked if they were a collection agency, and I spoke with linda armstrong who stated that they were an investment group and they were a group of paralegal's who do legal paperwork for a group of lawyers... is this accurate? I also asked for the website address and she didn't know it, she put me on hold for about 2 minutes and came back and said they just changed the website and gave me www.payiag.com, which of course gives no information. Well any help would be greatly appreciated! feel free to leave a message here, or email me at [email]motoxer271@yahoo.com[/email]

Thanks!