Huge regret for upgrading over the phone

I've just upgraded my contract over the phone and I realized after I ended the call that I did not select the colour of the phone. When I called back, I was sent from pillar to post, just to make a choice of the phone. I do not know why the lady did not give me an option to start with. I probably spoke to 10 people including twice with the retention department and at one point I was told to cancel the contract and start afresh with MTN direct. But every time I was transferred to a wrong department that did not want to take responsibility. I am tired, can I just get the colour of the phone that I want or cancel the contract altogether?