Business personal keep making mistakes

The persons working for this business just don't READ what is in front of them and possibly also type the wrong information into their system. My HUSBAND - MALE had to go for blood tests last year and we were changing medical aids so had to do it as a private patient. So after the operation, while on a new medical aid, they had to do blood tests again. They didn't look at the information on the hospital sticker to send it to the medical aid. Instead they sent the account to us as private persons. So we went to their offices in our town and they supposedly corrected it. But no, we got a claims notification from the medical aid that they won't pay as they entered a code which conflicts with the gender???? of the patient. How on earth do people who supposedly work with these things daily, keep on getting it wrong and may cause for us to have to pay the account in the end? Why do we have a medical aid if the service providers keep on making mistakes (they were not the only service provider who made mistakes connected to the operation) and then the members end up having to pay the accounts?