In-Hospital claim rejected

On the 19th of October 2019, I underwent emergency abscess drainage at Durbanville Medi Clinic hospital. At the time, my abscess was so large and dangerous that we were forced to proceed according to the attending maxilo-facial surgeon's schedule. I paid my co-payment and according to my plan Momentum Custom, all in-hospital procedures are covered. To this day, I am still receiving emails from the health care provider saying that I am now liable for this IN-HOSPITAL procedure. Momentum simply rejects the claim each time they submit and say that it was performed OUT-OF-HOSPITAL. Which is in fact, a total and complete lie. My abscess was drained WHILE I was in hospital. No, my husband is worried that he will be blacklisted because Momentum won't do their job! Why are we paying over R6000 per month and they can simply reject as and how they feel.