one last problem

I have almost got my life back. A year ago, I had $11,000 in payday loans, and almost $30,000 in unsecured debt. I was going negative in my bank account the day my check went in. I almost lost my car. That was a wake up call. With the help of my bank, I have reclaimed my life. They froze my checking account. I sent letters to all payday loan companies that were not legal in my state, and to my surprise, I started to receive paid in full letters. A family member paid all of my unsecured debt and I am repaying him now at zero interest. I want to pay my bills. I just could not afford 99% interest with cash call, and other bad loans like that. I was drowning. I have one final payday loan haunting me with phone calls. The original creditor was Check n go. I owed them $1500, and I paid them $500 last summer on an arrangement. In September, they had evidently sold me to a collection agency who offered to settle for $700. I did not have $700 but I did pay another $100 toward the debt. Now, I have settled with everyone but them, and started getting phone calls in April. I made another $100 payment, and was going to try and pay it in 6 months, at $75 a month. But when my relative paid all of my debt, he now pays my bills and I do not see my check. I think this is yet another collection agency, and they are threatening legal action. I know that Check n Go is legal in my state, but once we get to the collection agency phase, what can I do to prevent true legal action? I am just a little low learning to live on very limited cash but having no bills is a blessing. Please advise.