That is a tough one...I don't know the company.
BUT I have read horror stories about people paying CA's and **after** they paid, the CA's suddenly start reporting to the CB.
Maybe reword the letter a little to say that they will NOT report at all?
I would recommend that you DV them first...this will give you some time Then, i would try to pay the OC and fAST.
If you know you owe the money, maybe you can try to pay the OC first, pull it back from the CA.... What is the OC reporting on your credit report?
never call them - they record all conversations.