BAD SERVICE AND FAULTY GADGETS

On the 6th of December I bought two Talefunken tablets at Mr. Price in Tzaneen. Today I gave them to my sons to use and not even 5 minutes after they were using it one of the tablets screen cracked in the middle of the screen it even made a malfunctioning sound. it doesn't have any signs of falling or hitting any objects. i then went to the store to report the issue after the consultant told me that i should kindly go to the store with my receipt and make an exchange. i got to the store and spoke to the manager who told me that he will have to book for repairs that will be at my expense. now I'm expected to PAY TO FIX an item that malfunctioned on its own. the store manager then proceeded to call his line managers, one of which refused to talk to me and the other one, named Prunella, blatantly called me irresponsible for not purchasing a screen protector. that doesn't even make sense considering the fact that it cracked on its own. this is absurd. I want a new tablet or my money back.