Customer service

Good day, I bought a Sinotec 55 inch Tv at Game store in Greenstone mall in 2017, then last week pop out a vertical lines, then on yesterday on the 05 May I took in my TV to game store at Greenstone mall then they check it while I was there with them and they saw those lines and I left my TV there with proof of my bank statement cause I didn't have a purchase slip, then they told me that it will take days cause they have to request a hard copy slip from their head office first , they after they check the TV they allow me to leave my TV with them ,it was before 12:00. This morning on the 06 May I receive a call from them they told me I must come and take my TV cause my TV it does have a crack and it's blank so they won't fix it, to my surprise when they check it while I was in store there was no crack and it was not blank. So I told them what happend after I left my TV cause it was not blank. What happened to the movement after I left my . TV. Please Hello Peter help me on this one. Regards Tebogo Moatshe