contract cancellation - term is up

I have had a 2 year contract with MTN since 2019 which ended in May 2022 my monthly debit order ussually that was the 7th monthly after the 7 May, i called MTN on the 12 May to be exact to cancel my contract and the consultant that was assisting did advise the new billing fees... 7 June debit order still goes off and I call MTN again was advised the contract was not cancelled, but the consultant can see that I called on the 12 May to cancel it. I then decided to return this amount with my bank. since the 7 June till today I have been calling MTN to cancel the contract and stop sending me messages that I owe them the June debit order as I have no contractual agreement with them as ussual every time you call, the agencies keep transfering you to pillar to post, ref: *** i then managed to speak to Katlego who did not assist me at all was on hold for 25mins and she told me that her manager Boldwin was also not available to assist me... honestly the service level at the MTN contact centre is shocking, I am still waiting to be contacted back as promised but all and all I just want the contract to be canceled as per my request in May and i want nothing to do with MTN