Has anyone tried using these online credit repair services?

There is a law firm that keeps popping up on websites that says they can improve your credit score. Has anyone actuallly tried this service. If so what was your experience with them? Am I better off trying to repair my credit myself.

Сredit repair workеd fine to fix my credit. They disputed and removed lots of bad items from my credit report. I used this service – buildcredit.ifastnet.com