Sony Xperia Z3 Screen Cracking

Good Day, I got a Sony Xperia Z3 from MTN Illanga, I have not had this phone for more than 2 weeks, the phone half and hour before I saw the phone it was working fine, the phone was on the table flat with nothing around it, a message came through but I did not read the message only after about 10 mins did I pick up the phone to read the message but I could not open the message, turned the phoned side ways and there is a single crack right across the screen, the phone still had the plastic on it when you buy the phone, I send a email to Quinton and Jonathan that evening explaining what had happened, I took the phone in the Tuesday after copying all the pics off from the computer, only to get their and their repair centre won't even book it in, then get a email from them this morning saying they phoned Sony service repair centre or tried calling and the phone won't go through but then they spoke to Sony and Quinton from MTN said that Sony said no they won't book it in either, then I funny enough get through to Sony and get told to send it in cause they know there is a problem with the screens cracking, please something needs to be done with this store.