I was in the same situation .. early november & december for a January flight. .. must have gone back n forth with local office over the phone atleast 10 times .
in the end i just showed up early at the airport and spoke to supervisor who told me to wait for the cashier, and it was a smooth process. literally 5 minutes and i used my qcredits for the upgrade.
airport was JFK, and it was a Y to J upgrade with Qsuites