Very Unfair Treatment of a client by Store Manager

I recently bought a flatscreen TV from Game Menlyn, this TV is equipped with 2x USB ports and works perfectly, except that when I connect an external HDD it works for 10mins then crashes. I returned the TV 3 days after purchase and in the process of exchanging the TV, the store manager got involved, who then called in a second store manager and his technical assistant who continually tried to bully me into believing that it was My fault, as I should have asked beforehand if the TV was compatible with an external HDD. The store manager REFUSES to refund, replace or exchange the TV if I cannot prove to him that I do not have viruses on my external HDD or Memory stick. He said, I can leave the TV there and he would send it in to be assessed by a 3rd party. I googled CPA act and showed him that in the ACT where he is obliged to refund/replace the TV for me, whereby his attitude started stinking even further. He said that as per CPA goods may only be returned in unopened packaging. I asked him where on the box does it say this TV is not compatible with an HDD, whereby he could not answer me, I then said: "now explain to me how I was supposed to know this, without opening the packaging?" A big fight later, I left with the TV and did not get assisted. I can only speak for myself, but I will not be setting foot in GAME Menlyn ever again, and I will make sure that none of my family will either. Customers are not supposed to be treated like ********* and embarrassed by store managers, that is pathetic and unacceptable.