IRS processed my amended return incorrectly

I filed an amended return to convert MFS to MFJ. Was supposed to receive a nice refund as a result. The amended return was received May 2023, but not processed until September 2024. However, it was processed incorrectly. Instead of looking at column C line 22 to see the refund total, they looked at column B line 11. this was the amount of tax my wife owed. The IRS did not look at the amount of payments and withholding we (column B line 12 and column C line 16). They took the amount from column B line 11 and decided that was an unpaid amount, to which they tacked on years of interest and sent me a bill. I have made half a dozen calls to them to try to get this fixed, but they are being beyond useless. They are now sending me threatening notices that I will have my wages garnished. Is there some recourse I have to speak with a competent person that can fix their mistake?