MTN ACCOUNTS MESS UP

I am a subscriber of MTN since 1996 and have always paid my account by debit order. I never had a problem with it. This past Tuesday the 4th of May 2021 MTN suspended my services citing non-payment for the months of March and April. After several calls I had to send them my bank statements showing that the payments went through. They made a mistake but I had to prove that I paid. Anyway my services were quickly restored, but I wasn't totally happy at their service and attitude which made me look at fault. Then when my Debit order went through for the next payment on the 7th May 2021, I was debited double! Again several calls later I could get no explanation for this. I am a pensioner and cannot afford to pay a company twice. MTN wants me to wait 72 hours while they resolve this issue. My wife had a similar experience with them a couple of years ago where they just debited her account all the time and i cannot afford to go through the same experience. Please can you assist? Thank you