Please Help! Ohio PDL

Hello, like most I got trapped in the never ending pay day loan cycle....I have several loans and found this website, and used the instructions to revoke ACH authorization and close my account down. I just recevied a phone call from a company called CMS & Associates stating they were hired as mediators to mediate a case that will be filed against my county court. This is for a payday loan I took with Plain Green Loans--it was a $250 loan I made several payments on and now allegedly owe $510.21 with fees. The representative from CMS & Associates advised that my account had been sold to a group of attorney's who buy these debts and sue the consumers. They provided me nothing in writing and said my case was to be filed in my county court on Monday if I didn't pay the amount in full before then, and that I could expect to be served an few days later. They stated they couldn't make payment arrangements with me because the attorney's know they can get more if they pursue me in court and I'd be looking at over $2,000 with court fees that they would garnish from my paycheck. I'm located in Ohio and was when taking this out. Has anyone dealt with this company and had a similar situation? I'm just wondering since this is the first time anyone, even plain green, has attempted to collect on this. They refuse to let me make partial payments and I'm not sure if really have a leg to stand on...can they do this? Any help or advice would be greatly appreciated.