****** money from us

We are very upset with this medical aid, when we origanally signed up we were paying the moto health medical aid in arears. I specifically told Bonitas and produce a letter which showed we were paying in a arears and that we cannot pay in advance as we cannot afford it. They said it was fine and that as long as we have proof. We signed up and then the first month of instalment they took double which is R10 000 +- which we were firstly not told and no where on their application form did they say they would do this. My husband spent close to 40min on the phone asking them to pay the one installment back as it is our lively hood (our grocery money) and all we were told it there is nothing they can do. I feel Bonitas has ****** from us and **** to us. The reason why we signed up was because they said we could pay in arears. I have the email correspondence and proof. so Bonitas I ask kindly that you pay us back and fix this matter or my next email will be to your CEO.