When I bought my latest phone a couple of years ago - Samsung S22, I also bought a set of screen protectors and an anti-shock holder.
I thought I would go to the local mall and get the Chinese guy to apply the screen protector for me, as it is very easy to get a speck of dust on the face if you're not careful.
I handed him my phone and protector and asked to him fit it. I was the only customer, and the Mall was nearly empty. He refused and said "We don't install customer supplied protectors" (in his Chinese accent of course)
I said that's OK, sell me one of yours and install it. He said they didn't have any in stock. To which I replied, "Oh look, I have one right here"
He still wouldn't do it for me.
So I told him to shove his phone covers and his pop-up stand up his arse, and that I will never shop with him again, and walked off.