Slightly off-topic as it doesn't apply to PO accounts (as far as I know), but banks do have a facility known as a Third Party Mandate, which is quick & easy to set up. Basically, the account holder signs a form authorising a named person (the "Third Party")to administer the account on their behalf, without removing their own control over the account. In practical terms it is very similar to having a joint account and it is a useful short-term solution while a full PoA is being processed.
As I say, I understand that it doesn't really help the OP but I hope others may find the info useful.
As I say, I understand that it doesn't really help the OP but I hope others may find the info useful.