Contract ended but still billed, cancelation process a nightmare. No clear information from agents, false information given, rude agents!

Very dissatisfied with the service I got from Vodacom. Took a contract 2021 which was supposed to be done by March 2023 yet they still billed me for that contract. When you call the Collections department, half the agents there don't even know what they are talking about. From December 2022 I've been calling only to get different information from different agents, ALL IN CONTRADICTION of each other. Today I called again after receiving the invoice, only to be told I was supposed to cancel the contract 30 days before end date and because I did not cancel, they are still going to bill me for the month of May even though I initiated the cancelation today 11 April 2023. This company is a *******! Will never recommend to anyone or do business with them myself. The cancelation agent sounded more like a **** than a person who wants to assist. Bombarding me with a lot of information that did not make sense all in aid to help me "save" money. Why do I even need to cancel a contract I've fully paid for in the first place? And did it not occur to them to make prior communication if that was the case? What a ****!