Very bad service!!! Misinformed.

I am an MTN customer for 26 years. Have upgraded several times and never had any bad service or complaints. This time I used a branch in East Rand MalI, and I am VERY DISSAPPOINTED. went for an upgrade at MTN East Rand Mall. The Huawei representative persuade me to upgrade to the Nova 10. I asked her if you can download all your apps on the new Nova 10 and she said yes, through Petal search and G-space. All my apps was transferred and worked except the Android Auto which I use to connect my phone to my car. I immediately told her that that is a very important app. She phone her manager and we were told that the only app that does not work is Android Auto. I wanted to cancel the upgrade and I was told by the Branch manager and Area Manager that I cannot return a phone that was opened and there is nothing wrong with it. The more I try to explain that I was misinformed about the apps that could be transferred, they insist that I did not specify which apps. My argument is the Rep did not specify either that some apps might not work. She said all apps can be transferred. What I cannot understand, Rivonia MTN and head office said that I can cancel the contract in the 7 working days because I was mis informed. Even Huawei said that they would have taken it back but because the contract is with MTN they cannot make that decision. I returned it the very next day of purchase and they refuse to cancel my upgrade or give me an alternative.