Can you explain by what process being a paying customer with Google Drive/Google One helps you recover your account if experiencing what OP described?
- Try to reach Google's One support instead of the generic Google Gsupport. Since they are paying customers, may be there are humans involved at some point.
- If that fails, the next move is to take the legal path. There are several ways of doing so before going to court. I assume that once so trivial reaches any lawyer of the company it will be fixed immediatelly. If it doesn't, given that the company has valuable and confidential information that's not accessible anymore the case could be strong enough to reach a judge, even if the amount itself is very low (20eur/year). It's expensive and will take time, but it's the best I can devise.