Impossible to cancel a contract and bad service

Please note that I send an email to cancel my contract (and get a refund) because MTN is not rendering their services (full data amount not being loaded or data going missing). I have logged multipal tickets to correct this with no helpful response or apology. Customer care stated I must send an email to *** to cancel my contract as the 135 number option 3 kept dropping the line. I did so on 01/10/2020 with no response. Yet after giving a full calendar month notice and no longer using MTN's device, they are still deducting a monthly fee. Would not recomend MTN as they make it impossible to cancel a contract ( not even talking about getting a refund).