Synchrony Financial Credit Card Complaint

Synchrony Financial Credit card department,

Sale of account Delaware

I sent them a letter agreeing to a payment offer of $110.00. On -/-/-, I received a letter saying they have sold the debt on -/-/- to a collection agency named " - - - ''. To top of it all, the debt has been sold for $400.00, which is almost 4 times their initial offer. This is the second time they sell this debt to agencies that have shown patterns of violating FCDPA rules. I need a clear answer as to how to settle this debt based on their initial offer.