Painful experience with Vodacom

I regret taking a Vodacom contract, it was a nightmare from inception. At 1st they gave me a device not suitable for my needs after I've explained to them what I need it for.

Now it was on a month to month basis and in June I eventually called to cancel it. When I called I was given instructions on what to do and what final amount to pay in order to terminate the contract successfully.

I followed all their instructions and paid the settlement but now I've just received a call to inform me that my account I***-9 is in arrears and I am still being billed and I've been handed over.