Not on Extended Benefit Health Network

Have been visiting the HEALth WorX in Carlswald for years now. They've always been on the Discovery Extended Benefit Network. Visited them again on 13 June - sick myself and two sick three year olds. NOTHING was paid by the medical aid because HealthWorx is no longer on this benefit network. Tried to get hold of the practice manager for 3 days now, no response. I want to understand why a family health medical centre would opt not to be on this benefit network anymore. I honestly do not want to see an alternative Dr in Midrand (who is on the network) without this Dr having a medical history on any one of us.