Cancellation never done

I cancelled my contract via vodacom cancellations dept in July 2018. A balance of R2560.37 was payable, payment was made and the cell number was to be placed on prepaid. In August 2018, I started received harrassing calls daily from MDB debt collectors, insisting that I owe Vodacom this has been an ongoing thing and now they are saying I am owing R8000. The surprising thing is that Vodacom deleted my number (the number you dialled does not exist), so how are they still billing me if i cannot use the phone. I went into the vodashop The Glen, they could not help me as they do not have access to view accounts. I then contracted Vodacom call centre and when they looked up my details I DID NOT EXIST ON THEIR SYSTEM. But then MDB is still harrassing me for monies I do not owe. Or how can I be owing if I do not exist on their systems? this is very annoying as I need this number for business and prefer it as prepaid. Between Vodacom and MDB they are dont know what is going on as none can give me a proper answer/ resolution to this issue. I am not prepared to pay for an non existent / cancelled account. Is Vodacom trying to ******* its customers.