Broken tv and service

I bought a sinquotec tv from game in February 2019. 3 weeks ago i had cleaned the screen after cleaning it i switched the tv on and the screen was full of lines. I brought the tv back to game and thet send it to the supplier who has now quoted me on replacing the screen as it is subsequently cracked. This tv was a display unit in game that was given to me as they had no other stock on hand. Iam no expected to pay R4000.00 to have the tv repaired which is still under warranty and guarentee. I have just been at the game store in vincent east london and to no avail will the assist in replacing the tv. I would like to know what i have to do. As this seems to be wrong to me the tv was only R5400 and i now have to pay R4000 which means it would than cost me R9500 for a tv that is only worth R4800.00. I am frustrated and feel that the service i have recieved is pathetic. I feek that due to the fact that this was a display tv it has been handled more than normal and now after i cleaned my screen as i do with all my tvs this has happend. Please advise on what i have to do.