Vodacom service - legal department - cancelation department = the WORST

I have cancelled my contract with Vodacom over a year ago, I was on the phone with a employee of vodacom which told me the exact amount I needed to pay, I went to the vodacom shop in illanga mall in nelspruit and paid the full amount which was over a R1000, the guy assured me over the phone that my contract was then cancelled and all is in order. The person in the vodacom shop confirmed. Now a year later I get a letter that I was handed over to MBD for R589.20 which was apparently outstanding. The service was very bad from vodacom, I phoned them but to no avail. They just wouldn't assist me. For about 3 months I didn't get airtime on that number and still paid it after I cancelled it. But when the vodacom employee told me it is all done now, i accepted it. But now I get this nonsense. Vodacom made the mistake, not me and I don't understand how I can be held responsible for their mistake. Vodacom service is the worst, I would suggest anyone to stay far away. They cannot even provide one with the recording of the conversation between the employee and I yet they "record" all conversations. I'm so dissatisfied and disappointed in their service.