I am willing to work with this law office who is collecting my debt for my American Express bill. It was originally $700.00 but they tacked on $2,000.00 in interest fees. I gave them $670.00 but I can't afford to give them another lump sum like that. I don't want my accounts frozen. What do I do?

First its not a good idea to piggyback your question on someone else's. This can lead to confusion. You should start a new thread. So I've moved your question to its own thread.

Did you reach a settlement with them before making payment? If not, that was a big mistake. You know have to negotiate a payment plan with them and get it in writing before you do anything more.