Very disappointed

Yesterday my Mom went to Shoprite Madela park Qwaqwa to buy a new phone, the cashier failed to explain that the phone only use MTN network. As soon as I realized that problem I took back the phone to shoprite, and I explained the problem with the manager. She refused to refund me or exchange the phone. She said their policy state no refund or exchange on cellphones. I’m very disappointed with this so called policy if it does exist. Now I’m stuck with that phone because I can’t use it.