R8000pm medical aid for two people not covering doctors hospital bills, PMB condition

My 77 year old dad who suffers from ischemic heart disease, acute diabetes, has an amputated leg, 20% eyesight in one eye and completely blind in the other, hearing impairment, poor kidney function amongst other illnesses; was admitted to hospital on the 26.09.2018. Despite all these illnesses, he tries his best to take care of himself, takes his meds religiously and has my mom, who herself is recovering from cancer, to watch over him. He goes periodically to all his medical appointments and therefore was no need for any hospitalization over the last couple years. He was admitted on the 26th of September this year due to irregular cardiac arrhythmia. He was hospitalized over the next few days to stabilize his heart. Shortly after his discharge, I started receiving emails - a number of bills from doctors, radiologists etc ALL OF WHOM WERE EITHER UNDER PAID OR NOT PAID AT ALL. My sisters and I pay R8000 per month for my parents medical aid, that is R8000 for two people only. As mentioned above there was no hospitalization for my parents in the recent few years. The one time this year my father goes to the hospital, we receive bills left right and centre. Firstly the condition under which he was hospitalized was PMB, there is no doubt or question about this. Secondly this plan is so expensive and should be comprehensive, yet there is always monies to pay. My parents are both pensioners and cannot afford a cent, and with their health conditions and age cannot be placed under these high amounts of stress, and Medshield always seems to be causing them worry and financial stresses. My sisters and I cannot afford any more, as we already pay more than we can afford on their medical aid. The point of a medical aid is a safety net, its not meant to be a source of constant stress. Carte Blanche has exposed schemes of not paying what they should in terms of PMB and it seems Medshield is no doubt one of those schemes. Us as consumers should not allow this, I want my dads bills rightfully sorted, failing which I will be taking this to CMS.