Making me pay twice for same tests same day

Ampath is insisting that I need to pay for the tests that the insurance company has already paid for. The doctor completed a form for the tests to be done for the insurance purposes and I took that along with the insurance company letter indicating that I needed those tests, the lady that helped me in their Umhlanga Medical Centre offices did not explain that I would be charged twice for the same tests because of the doctor's form. How can they draw blood on the same day and charge two entities for the same?!