Broken screen tv

I bought a 70 inch Hisense tv at game ilanga mall Mbombela. Upon receiving the tv we switched it on with the game delivery guy and it was fine while in the box. I then installed it with my accredited installer and upon switching it on again the tv was cracked , it shows blurry colorful lines as if it fell or experienced trauma, yet nothing like that happened. I took it back to game the following day and noticed abit of damage on the box. The sales reps and manager argued that as soon as the tv leaves the store it’s my responsibility. My argument is that either I was sold a tv of questionable quality or something happened to it. They booked it in and after 3 weeks they are telling me that they will not compensate me , after the store manager at game promised me that I would either be refunded or get a replacement. They strung me along for almost a month. I have another plasma and my one year old has hit it with several objects but it did not crack or do anything, so in this case what happened to the tv? Hisense I’m not happy. 11k is a lot of money for something that i didn’t even use once.