vodacom not taking ownership.

last august my contract came to an end however Vodacom kept on debiting until i called in September and inquired and was told i was suppose to call to cancel which i wasn't told in the beginning of the contract ,then i was told the last debit will go off in October as i called in late which happened then everything was back to normal ,in November they debited again when i called no one knew where the billing was coming from in December they didn't debit then in January and February they debited ,when i called in i was told i was on prepaid they don't see my statement then i was transferred to accounts where i didn't' get any help only transferred to the survey ,I've been calling and all the people in the call center and contract cancellation department told me they were unable to check my statement as I'm on prepaid however when they transfer me i don't get any help only being placed on hold then to the survey this is bad as it is ruining my credit record as i keep on going back to reverse this debit and being charged a fee for the reversal,please assist as i wont be able to pay for what i don't know and they are unable to explain as well.