Vodacom are a bunch of *******

Upgraded my contracts in September 2018 billed the same month for the new contracts but the contracts that i cancelled are still being billed for. One months notice is what you have to give for a cancellation, i am still being billed in January 2019 for the contracts that were supposed to be cancelled. Since I have done the upgrade (stayed on the same package) my contract is no longer big enough and i now get billed out of bundle rates, my contract runs out around the 20th of the month. I took a special on data contract but am still being billed at the old rates. When my account manager tries to contact the accounts department they give him the run around (the company's own employee) how much chance do I have of sorting this mess out. Vodacom owes me a refund on the over-billing of my account for the past 3 months.