bad service

I went in on the 23 of May to buy a cover for my Samsung S6. Attendant offered me a screen guard and I agreed to take it. She promptly asked for payment before starting to apply the guard. When it was app**** I noticed that all around the edge of the screen guard, there was a fine line of blotchiness. Almost like it did not tack at the edges. I told her that I could not live with the fact the I am spoiling a beautiful screen. She said that I could not get a refund as according to her, thats how it was supposed to fit. I asked her to remove it as I was not happy. Manager was not around. I called the Manager during the week and he then told me that the attendant said that the screen guard fitted perfectly. This was a lie as my wife was with me at the time and attendant was not around when I visited the Manager. And he would only make a decision once he sees another screen guard fitted to the same type of phone. Preposterous, right? He was also adamant that his staff could not make a mistake during the fitment as they were that good. I asked him, why would I have it removed if it fitted perfectly. He had no response for that. I have not heard from the Manager Steven again.