Worst Admin and customer service ever

I have moved from medical aids 2019, receive an account saying I owe them (Fedhealth) money from savings pocket. I send all recons, that I managed to get from every doctor, hospital, x-ray department etc. If I phone the medical aid I get sent around and if you loose your cool and ask to speak to someone higher up they just say there is no one in the office and they will leave a message to contact you. How can this be you quality of service. Where the client has to do all the work, it is ridiculous to say the least. This has been going on for more than five months. Needless to say I moved because of bad service, but unfortunately it seems like I cant get rid of the bad service even after moving away.