Wrong codes for procedures

My friend of 88 received an account that has not been paid by her medical aid, AECI. Contacting all involved I learned it is because Ampath is using an in-hospital code for a urine test that was sent in by our doctor because of constant bladder infection. Francina from AECI says they can not pay it until Ampath adjust the code and Ampath just says if the medical aid does not pay, the patient is responsible. Why don't they have the right codes for in and out hospital. I want them to fix this!!!