Cell C *****s R4000.00 from customer!

I upgraded my cell c contract in 2014 and it was suppose to end month end of February 2017. Cell c kept on debiting from by dads account and debiting the same amount of money even when the contract had ended. I went to the store (The glen shopping mall) and they told me to call the cancellation department and my dad did that. They told me that the contract wont end until my dad calls and ends it and he did that. End of March their debited again and my dad went to reverse the debit as their said they will stop debiting. When he called again, they told him that he shouldn't have reversed the amount, how so because the contract ended and he called to cancel it. they then gave him a story that he must wait 3 months after since he reversed the cancellation wont go through. end of July he called again and cancelled and they gave him some excuse that he must wait 30 working days and the cancellation will go through and it didn't! End of August he called again and they told him that they will cancel in 72 hours. 5 days passed and still no cancellation. please assist case these people are ripping my dad off we recall do not know what to do now.