Medihelp are the worst medical aid EVER

I have had endless problems with Medihelp not paying claims that are considered PMB. I am sent from pillar to post with them, when the claim gets rejected by Medihelp I forward it to my GAP cover only to be told they cannot assist with the claim as by law Medihelp should cover the claim as PMB. It then takes months to resolve whilst the service provider hands the account over for non payment due to no fault of my own. I have had to procedures in the past year including and emergency appendectomy that I have had endless issues getting resolved. what sort of recourse do I have? I'm beyond feud with their lack of service and their underhanded manner in which they deal with claims. If I didn't question any of this they would happily have me pay for medical expenses that they are required to pay by law.