Sent letter one month ago asking to remove mistake. What do I do?

I sent to a creditor that was paid as a agreement asking them to remove this from my credit report. It has been over a month and I have not heard back from them. What is my next step.I also sent a letter to a company I owe money to to settle in full it also has been well over a month I have heard nothing. What is my next step.
-------------------------
hopefully you sent it certified delivery so you can prove they got the letters
the next obvious thing to do would be CALL THEM and ask.
------------------------
certified return receipt I have the returned receipt. What do I tell them on the phone?
-----------------------
what the hey
fix it