Urgent: Immediate Denial of Secondary User and Lack of Response from Verification Team

We have tried to add a secondary user to our UK & EU account, which we have done successfully in the past. However, this time the user was denied immediately, despite their information being correct. When we reached out for help, we were advised to email the verification team and expect a reply within 17 days. Unfortunately, after sending multiple follow-up emails and waiting over a month, we have received no response. We have also opened seven cases to seek clarification, but each time we were told that only the verification team can assist us. This situation has been very frustrating, and we urgently need this account set up.

Has anyone else experienced their secondary user being denied immediately, and how did you resolve it? Any advice would be appreciated.