Dissapointed after being loyal for long

I have been with MTN ever since I had a cellphone. received great service. took multiple contracts, and avoided other service providers, reciprocating the same loyalty. but I think they take it for granted our loyalty to them. They failed to reverse an incorrect purchase to my old number that is no longer in use. yet the funds they can see, and they have the power to reverse them. on a silly technicality that the number should be at least wrong with 3 digits to make the reversal. I think its time to cancel contracts with mtn, and look for a better service provider.