Hi-Fi Corporation disservice

Two months I purchased an Asus PC at hi-fi corporation at Mall of the North Polokwane. I am not happy with the brand of the PC, when I switched on the PC and suddenly there were white lines on the screen, and it kept getting worse. I took it back to the store they called it negligence which means I'm responsible for the condition of the screen. I was so confused how because the screen does not have a crack or ink spill on the screen. I was told if I want to fix it i had to pay. I am a student I need a PC for school .It is clear that the screen is faulty and am not responsible please assist.

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