Go to another hospital

Most unhelpful, been trying to get an invoice for a co-payment for weeks now so that I can claim back from GAP cover but wow, these people just don't help. All I ask for is the actual co-payment invoice, of which I am entitled to. They clearly don't care, which is concerning. I am sure if I owed them money they would be hounding me! Very disappointing and quite shocking that they cannot provide a simple invoice for a payment that was made.