Vodacom are huge cheats

Vodacom are big cheats. They tell me that my account has been in arrears since March. I have bank statements stating that the money was debited and they give me a story saying that the money bounced on the 5th. I had not paid for April and May due to the national lockdown. I should only be in arrears for April and May only. Now they are charging me crazy penalties which I was not informed of. They did not inform me prior that they were having issues with my account, until I called them myself. I don't understand why I as a client have to run behind them and sort out their mistakes. I do not have an issue paying for April and May but March was paid for and they are cheating.