ABC Payday loan

I took out a payday loan with ABC payday losn. I have not finished paying on it yet. They say I owe 590 but will settle for 413. I borrowed 350 and made 2 payments of 105. My account has been closed so they don't have access but they keep calling me at work and my friends and family. I want to pay them back but cannot make the payments they are asking for. I do not have a debit card so the women told me to get a prepaid card. Can't I just mail them money orders?
Any help would be much appreciated.
Thanks!