Unauthorised debit order from Vodacom

On the 27th May 2020, I was contacted by a Vodacom sales representative and they convinced me to enter into a portable Wi-Fi Vodacom contract. I was informed that it would be delivered within 7 to 10 working days . By the end of June 2020, Vodacom delivered the incorrect portable Wi-Fi device then everything was cancelled, even on Vodacom's system it shows everything is cancelled however my bank account is still being debited every month. I have to incur cost every month to reverse the debit order with my bank. I called Vodacom multiple times and also went to their head offices in Midrand but no one is able to help me, i kept on being referred to someone but no one is assisting me. It is frustrating and annoying and I cannot understand how Vodacom cannot cancel the debit order in their own system. I have been paying for a contract i don't have for 5 months.