DENIS DOES NOT ASSIST BONITAS MEMBERS AND NEEDS TO BE TAKEN TO TASK

I am very frustrated with DENIS. All they ever do is not pay for services with the excuse that it is not covered by my Medical Aid. In December I saw a Periodontist who recommended that my 4 Wisdom Teeth be extracted. I had to cover more than 50% of the Periodontists bill because DENIS did not cover most of it. I opted to sit in the chair and have all 4 Wisdom Teeth removed in one go with the hope that DENIS would pay for this. Needless to say they again covered only around 50% of the claim. I was told that the practice used the wrong codes for of the claim lines and that they need to resubmit it and it would be paid. THEY HAVE STILL NOT PAID IT. I have had it with DENIS and a I am requesting advice from fellow members to take this forward. How do I contact the Ombudsman? What other options do I have to follow. Please advise.