contract cancellation nightmare

I reported ***** on my account last in July 2017 regarding an upgrade that was done on my account without my consent. I never received feedback regarding the ***** case for months. On the 9/3/2018 I went to Vodacom Northgate to ask about the account status as on the ITC it was reflecting I owe Vodacom R636.57, which I paid in frustration as I never received a statement in over 6 months. I there after requested for the requested for the contract to be cancelled which took me a few weeks to be done. Today I contact Vodacom accounts regarding the paid-up to my surprise i'm being told that I owe Vodacom again R77 and to my knowledge i paid the account in full, when disputing this amount I am being sent from pillar to post. Vodacom is the worst Telecommunications company ever, I regret the day i went into contract with them.