Unauthorized upgraded package

My father had two contracts on his name. One for me and one for my brother. My brother then upgraded his package, but MTN made the mistake and upgraded my package instead.The day after, I then transferred my contract to my name and my brothers package remained on my fathers name .I paid for a upgrade that was never authorized. Then for two to three months after that I was billed for both brothers upgraded account and my (unauthorized) upgraded account. I am struggling for about four months now, to get a refund.