Discovery Cancelling my Medical aid

I received an email the 14th December to say my Medical aid has been cancelled, when I phoned in to find out why, they said my employer back dated and cancelled it from September, So not only was I unaware of them cancelling the membership but they allowed my previous employer to backdate and cancel it, they said I need to pay for Sept, Oct, Nov and December in order to active it again.But how am I suppose to just find 4 months premiums in December month of all months. Then on top of it, they called me now to tell me they cancelling the entire membership and they will be subtracting my claims against my premiums, then the difference they will pay top my employer and not me, but I explained to them that my employer will never give me that money back, they said they don't care I must take it up with that companies HR.They said the reason they are cancelling is because I have back problems and they were not aware of it,which I wasn't either until I went to the Dr and they sent me for X-rays and it turns out I have mild scoliosis,this was now in December. They said that this condition I knew about and I was treating it out of my own so they will be cancelling my membership. Ridiculous!