Horrible Customer Service!

I have been on a back and forth with MTN from the 9 of February to date. My 36 months contract with them was supposed to end last month. However, according to their system it only ends in May. My contract was initiated on the 25th of February 2020. I have emailed them the original contract to prove that. I received my first invoice from them in March of 2020 which I have also emailed to them. Now from that period until now, my contract was supposed to have come to an end. But somehow, they expect me to pay for 3 more months because of an error that happened on their end. 2 months and multiple reference numbers later and my issue has still not been resolved.