MONDO- horrible service- I want it cancelled!!!!!

MTN and their partner called MONDO and offered me a sim only deal, i was specific on the call that I will take it on condition that it is on my existing MTN number as I do not want a third number. They assured me this would be done- weeks after the sim was delivered I went to Rica it at mtn store and was told it had a different number. I have spent almost a month explaining same story to sales , retentions , contract department after holding phone for more than 15 minutes each day . I am so upset that I want this to be cancelled immediately - this is poor customer management and each time you finally reach someone , you have to repeat same story and given same feedback that it will be resolved. Worst every experience with MTN