Billing while contract ended

Good Day<br> <br> I had a contract with Vodacom which ended on the 20th August 2015 but they debited my account on the 01 October 2015 even though the contract is no longer in place. I called the call centre to find out why are they deducting my account and there is a balance of R1000 showing as outstanding amount on my bank statement. Both Vodashop and Call Centre cant see this outstanding balance and the debited amount. I spentabout 2 hours today trying to sort this out but no one could help me. I find it strange for Vodacom to be busy debiting my account while I no longer have a contract since 21th August 2015. <br>