Customer Service

I bought a new pop socket for my phone today for $10 and the young man working there put it on for me at my request, he was nice and so was the young lady that was there. But when I got home about an hour later, the pop socket pulled right off the phone. I called the store and told them about it not sticking and that I wanted a refund so I can go buy a different brand or type somewhere else so I can get one that stays stuck on the phone. But I was denied a refund and denied a replacement for it too! I'm extremely dissatisfied with that kind of treatment after being a faithful customer for the last 9 months and paying for something that doesn't work is very upsetting. It was the store in Reseda CA at the intersection of Saticoy and Tampa. I need this corrected or I will have to take my business elsewhere and that would be very disappointing to me. Thank you.