Poor service

I have a phone contract with mtn, on my husband's name but my account, I pay the account.They keep on debiting money from my account ,they can see that I'm in a minus on their side ,but they still keep on debiting.They owe me now R2735.40 ,they debit again on the 28th of December R1769,50 money that belongs to my funeral policies.Customer care keep on telling me that they will take it up with the accounts or banking department,but still nothing happens, I've been struggling for months now with mtn,and I really need my money refunded