Efiled federal return being rejected  (ERROR IND-180-01) saying primary taxpayer's IPPIN doesn't match the efile database.  I have checked that it was entered properly three times, and efiled it twice.  Taxpayer and spouse also sent me copies of their letters from the IRS and those numbers match the entries I made.  The numbers provided say they are for the 2021 tax returns, which is what I'm doing.  I know it is for the right year, and they have not moved.  Their address is the same as their 2019-20 tax returns.

I can't get through to the IRS or to the Taxpayer Advocates Office.  Other than filing by mail, are there any other options I have?