Tfg Donna mobile exchanges

Hi guys my wife recently went to Donna stores in Parow to buy a phone she asked Jody the sales assistant for the hi boost up device she brought her the hi boost go device and was told by Jody that it's the correct device Jody took off the tamper sticker and proceeded to put on the screen cover etc when my wife got home she took the cellphone out of the box and that was when she realised the device wasn't the hi boost up she wanted so she switched of the device left everything as is and proceeded to go back to the store the next day,she to the very same sales assistant told her that you sold me the wrong device and would like to exchange it for the hi boost up device Jody then proceeded to tell me they don't do exchanges and the tamper sticker is already broken I told her you took it off yesterday she says she sorry but she can't take it back I left the store then contacted HMR which they sent me CPA forms to fill out as I informed them I'm very unhappy about the matter and I really want the hi boost up device and I feel I was well in my right to exchange the device but was turned away it's been days now and no one has contacted me can anyone help me please.Roxanne