Account overcharged

I upgraded my cell phone contracts on the 10 November 2014 and signed on for two contract Samsung S4 Active phones on a Top up contract at R199.00x2 = R398.00 a month. I authorised Autopage to deduct that amount off my account monthly. On the 31 December 2014, Autopage debited R2608.00 from my account. I then went into the store to query it . Bilal, the Manager at Autopage assured me that he will sort the probkem out. On the 30/01/2015, Autopage then tried to debit R4185.52 off my account and then tried again on the 27/02/2015 to debit my account by R4185.52. When they could debit that money, they then on the same day debited my account by R266.21 which I had my bank reverse.. They have suspended my account a few times saying that I am in arrears when in fact they owe me money. Bilal the manager keeps saying that this matter will be resolved but I have had no joy. I have had to take ny money out of bank account in fear that Autopage will just debit my account. I did not authorise Autopage to take out more than my contract amount which is only R398.00 a month.