worst customer service ever

I went to the cellc c store in sandton city on the 29/01/2016 to buy the screen protector for my phone, the consultant helped in fitting to my phone but as it turns out it was defective and I was told to come back before seven days should it starts to peel off, it started peeling off just when I left the store and today when I go back to have it replaced then I'm told they are out of stock and don't know when they will get stock but was advised to go to the mtn store and purchase a new one from there. the refund was done to my card but I given a wrong information that the money is available already for purchase and when I get to the mtn store the card declines and when I return to the store I was met with some stinky attitude from the guy who assisted me Patrick and made me look like a fool in front of all the customers and frankly it's not the first time he has ever done that to a point where each time I go to that store I refuse to be assisted by him, now should anything happen to my screen who is going to take responsibility because he confiscated the one I previously bought.