Worst accounts process and terrible customer service with accounts settlement

I had a Vodacom contract a few years that I did not upgrade when the offer was made and requested to stop monthly order so that i could move onto prepaid only. 2 years later after absolutely no correspondence from Vodacom I was told by my bank that I apparently owe Vodacom R677. I never missed a payment during my contract, and requested that my contract be stopped as i did not have regular income at this stage and could not keep any accounts. They kept sending me top up airtime after i asked to stop/cancel the contract. by now i have moved on to another provider by now, so I found it strange that i was still owing Vodacom anything. I went to a Vodacom shop who then advised to go to my bank to get a statement to prove that i had been debited incorrectly. the bank found no trace of any Vodacom payments. i then had to go back to Vodacom to further query for some sort of record of the debt. the sales rep then put me through to a debt collections agent who then took my details and said that i would be sent a settlement statement via email in 48 hours and that the debt would be cleared off my name in 21days. its 3 weeks later and I have not been given any settlement statement and the R677 still stands against my name with no explanation, billing or record to prove it. I can't recover my credit score to apply for some much needed finance and can't get through to anyone when i phone the accounts number to get more details. It's I'm being kept in a chokehold, expected to pay to an account with no record, after my requested cancellation of contract was ignored 2 years ago. This experience is terrible as i need to make application for finance on a much needed car amongst other things and Vodacom is not helping solve a problem they created. I don't understand why i have not received any email or settlement statement from them yet. my hands this is a major inconvenience both financially and time wasting as i am being sent in circles month by month with no progress.