MTN taking advantage

I have a bad experience with MTN, I was double charged last year for 4 months and I complained, sent statements and nothing was done. Now they do not top up with the data I signed for 20GB less, I complained on May and today(2022/06/22) they advised my previous query is still pending they will do a follow-up, the question I ask is for how long will MTN keep on ******** the poor and nothing is done about it. One problem after the next.