Mr P Mobile USELESS

I bought a cell phone on Sunday at Mr Price. The Supervisor who helped me didn't tell me that it is Network Locked. I went back an hour later to find out how to insert the SIM and use the phone. They told me that I can't return the phone. The sales person Nicky assured me that I can use my current sim card which is Telkom. It was loaded as a second SIM. I can not access the data on my second SIM for data. It will not allow me. YOUR SALES PEOPLE AND MANAGERS NEED TO TELL THE CLIENTS IT IS NETWORK LOGGED. I have wasted money on a phone that I can't use and I am not allowed to return it because it is 'not faulty'. If they had told me the right info I wouldn't have bought it but they can't fix their problem because of internal policies!!!! DISGUSTING SERVICE!!!!!!! What must i do with this piece of @#$% phone now?