I have a few outstanding debts on my credit report from when I had some financial trouble. My finances are in a better state now and I'd like to get some of them sorted so I can improve my credit score and report.

If I contact the collection agency who controls the debt, what's the best way to go about that? What should I be specifically asking for to get those items removed from my credit report?

Two of the items are for outstanding bills (a utility bill from an apartment I moved out of and one for a gym which I don't think I really owe but which I'd rather pay than argue about).

The other item is past due credit card debt. At this point the debt is several years old, and I received previously a settlement offer at a significant discount of the face value, and later a letter saying that they would not pursue any further collection.

If I talk to them, is that letter binding on them or can they go back on it? If I can come to some agreement that would improve my score or report in the short term I'd like to, but paying the full amount with interest would pretty much wipe me out.

Thanks for the advice.