on-line payday loan help!!!

I live in Mass. and had 4 pay day loans that all defaulted, I lost my job and my bank account was closed by the bank. I have paid back 2 through a notification from a law office and 2 through a treatening call to have me arrested tomorrow if I do not pay today by federal agents. The company that calls is United investigations and they want me to pay back $2333.33 on a $300 loan from eht end of March. They can not give me the name of the company I took it with because the cover over 1400 comapnies, they can not give me the actual date of the loan and will only take payment from a Walmart debit card since I have no credit cards. The payments I already made were more than triple the amount I borrowed and now I think I am getting schamed. Will I get arrested tomorrow? I do not know the name of the on line loan which all were done on line and now and sick to my stomach that a) I paid them in the past and should not have or B) will be arrested tomorrow.