Cancellations - Bad Service

I called Vodacom on the 15 January 2026 to cancel my contract. Which means 1 February 2026 supposed to be my last debit order. Now I get an SMS saying that 1 March will be the last debit order. They said its a 1 month notice period, meaning January invoice is paid on the 1 February 2026. February 2026 will be paid in 1 March 2026. I already did my one months cancellation. The agent did not explain that 1 month counts from the end of the month and not from the day of the call.