MTN - Please cancel the debt and activate my service

I have upgraded my contract with MTN in March 2022. I took a contract with a premium of R839. Sometime in April I got a debit of R2700. I called MTN and they said it was a mistake and it will be rectified. I again got debited another R2500 plus in May and I called MTN again and they said the same story and finally refunded me. 3 months down the line I realized my services were cut off. I called they said they will fix it. My debit kept on going through and I was over charged. Of late the debit amount was slightly lower and today my services are cut off again and MTN says I owe them R13 000 plus. These amounts don’t reflect on my MTN App.