Over charged at MTN

The service im receding at mntn is poor. I am being over charged on my monthly contract with mtn i was migrated to a new plan that without my consent I have contacted the contract center to change back and refund the extra money charged to my account they move me to the next consultant without real assistance .I have told them I cannot i afford the plan they migrated me into they still have not changed the plan nor have they given me a credit. This has been going on since March 2026