It would be screwed up if it was up to the CS agencies to make those changes without a court order. I'm a CP and always have been, but my x called CSE and told them that it was an error and that she was supposed to receive the CS, not me. They simply believed her and stopped sending me the checks, sending her own checks back to her, as well as all correspondence. At tax time, they took the refund money from me, not her!
You don't need to pay for some expensive lawyer. Go to the courthouse ASAP and resolve this. It is simple, but you have to get this in front of the judge and do it the right way.
Go pro se or get a paralegal. Stop losing dollars to save pennies.