Vodacom Cancellations Nightmare

I never knew that cancelling a contract would be such a nightmare. I took out a 36month contract with Vodacom which came to an end on 5 September 2020. On 4th August, I called to cancel the contract (with more than 20 days notice as stipulated in my contract). After trying to sell me a renewal (which I declined) they then tell me that they cant process the cancellation as yet, and I should call back beginning of September. I had received data the beginning of August, debit order goes off 28 August and I receive more data at the beginning of September again. I called them on 1 September again to process the cancellation. The agent explains that the contract is now cancelled and that there will be no debit order processed for end September. 11 September, I receive my statement which shows I'm still paying for the full contract (for the device and the data) which I again call to query. The agent then tells me that I called to late for the cancellation. LIKE WHAT!!!! Going into the store was deemed pointless as well. After another 5 calls, the contract was migrated to contract, I overpaid Vodacom (but they wont admit it), and now I am hoping I will not have another debit at the end of this month.