vodacom offended me

I'm not too sure how many times did I do this with Vodacom but it's fine I will do it again. I've been sending emails doing calls regarding the contract phone that I took in 2018 and that I paid for in that past 24 months. Now in December I upgrading my contract and that is when I was told that I have an outstanding amount and I told them that I was paying the account even after the contract ended as I wanted to take the upgrade. The consultant that I spoke to recommended that I don't cancel the contract I can run with it as I wanted to do an upgrade but I regret taking that decision as I am where I am because of that decision. In December while I was busy with it and seeing that I was send from pillar to post I decided to cancel it now I'm being told that I owe them R2038.00 while I was the one who was doing the follow ups with them. I'm tired of this please can I get help regarding this matter