Administration inefficiency

My son was due to go for an operation on 12 May 2020. Due to the pandemic, he was required to have a COVID-19 test prior to the operation. He went for a COVID-19 test at Lancet on 8 May 2020. We enquired as to whether he should rather have the test closer to the the operation, however the lab insisted that he have it on the day as it would allow time for the test to be processed. This test was paid for by my medical aid. On the date of the op (12 May 2020) the hospital refused him entry as he was supposed to have had the test 48 hours prior to admission. It was determined that the hospital had not communicated the criteria to the lab. The op was rescheduled and the lab redid the test. The hospital accepted responsibility for payment of the second test on the day and have subsequently confirmed this in writing. The lab however did not put the account for the hospital, but rather put my details. They have subsequently invoiced me for payment and continue to harrass me for payment even though I have provided them with evidence that the hospital will be paying for the test. I cannot get them to invoice the hospital directly.

The hospital is willing to pay, but need to be invoiced!