My Samsung stopped charging. My wife took it to the Verizon store on Ward's Rd in Lynchburg, VA. Rude and insolent lout refused to even look at the phone and pointed to the Batteries R Us across the street. If the phone could not be repaired we were prepared to buy a new one. We still might, but certainly not from this location, and likely not Verizon.
Stores don't fix phones, they only sell them. You were pointed to a store that specializes in batteries because focusing on a phone with issues at a store would have been wasting both of your time.
If your phone physically looks fine and worked for you, I'd consider DIY. Much cheaper buying a battery yourself and an ifixit kit to work on the phone.
I'm definitely sorry to hear you are having issues with your phone. We want to make sure you can count on that device. We're glad to help solve the issue. Is the phone still not charging? Have we tried multiple chargers to see if that makes any difference?