TL:DR I am filing a form 9423 in response to a CP504 where the tax liability has already been paid. Anything else that I should do?
There was a typographical error in my minor child's social security number on their 2024 tax return. The original balance was paid on time. I received a CP54G to correct the SSN and I did so. I then received CP14, CP501, CP503, and CP504. After receiving the CP14 I called the IRS and after waiting on hold for 1.5 hours, I was told that there was no balance showing and that I did not need to do anything further. After receiving subsequent notices CP501 and CP503, I called again and the agent figured out that the payment was showing under the incorrect SSN and the return information was showing under the correct SSN. She told me to write a letter to the IRS office on the CP503. I wrote a letter, but about 2 weeks after the IRS office received my letter, I received CP504. I am writing another letter and including form 9423. I would really like to get this straightened out over the phone rather than waiting for a response to snail mail. Should I call the IRS again? Is there any way to find the "right" person at the IRS who has the authority to fix this? Should I contact the tax advocate's office?