Debiting my account

I have been with bonitas for 6 years and every year i was asked to do an income verification. Every year i have filled in the forms and submitted it in and i never filled out anything for my wife as she is unemployed. After submitting all my document i got an email from them saying that i will be debited in the highest bracket cause they didn't receive my documents. so i phoned them and the consultant i spoke to checked on their system and assured me that all was well and they had received my documents and i will be debited in my bracket and not the highest income bracket. In February i got my monthly statement and they have debited me in the highest bracket. So i phoned them and then they tell me i need to submit an affidavit to say my wife is not working where as i have never done so in the past 6 years and didn't have this problem. Anyway i did give them an affidavit and requested that they refund me. I have phoned and email on numerous occasions and up to date no one has come back to me.