They can do nothing YOU can not do unless laziness prohibits you becoming involved in FIXING something you messed up, your credit.

Get all three credit reports and go over each one at a time. Dispute errors, IN YOUR OWN words not some letter you find on the inernet, then go on to the next report and do the same.

You can negotiate pay to deletes in some cases with the collection agency/creditor but this must be given to you in writing before a dime is paid.

That is ALL a credit repair place can do.

A good credit repair service, should help you get your credit affair in order, but not guarantee that there will be deletion of certain items on your credit report. They should help you figure out your credit affair, also.