GIFT is a lie

I was contacted by MTN as I have been with them for over 15 years. With more than one contract. They said 2 of my contracts qualify for a gift which consists of 2 Nova 73 phones on each contract. One of the contract was due for an upgrade. When this was attempted I was informed the 2 Nova phones WAS the upgrade. This is not what was conveyd to me in the conversation. When I was told I am such a good client of more than 15 years. I have given the 2 phones back and was then told I must pay a cancelation fee. This is unacceptable as I DID NOT REQUEST AN UPGRADE IT WAS EXPLICITLY EXPLAINED TO ME TO BE A GIFT. I have now been struggling for about 3 weeks to get the matter resolved. Still I am being told it's either under investigation or I need to go into the branch