You would need to leave at least one in place so we have something to look at. If you want to create one yourself, then provide a new example, we can certainly look from that instead. Alternatively, if your user is awaiting access, can you not give them the user group access without marking that invoice temporarily?
Please note, our standard support (not advanced) can be up to 72 hours. Advanced can take longer at times. So you will need to have something in place for some time.
Im not sure what you mean on this part, as I havent provided an email.