LG Muziq / AX-565 / UX-565

Has anyone had any problems with this phone silencing? I have a customer that purchased this phone the day it came out. After a day of owning the phone his buttons on the side that you would normally push to silence the phone stopped working as well as inside the phone you have the option to ignore or silence. There was no way to silence it so we swapped it a couple days later for another thinking it was just the phone. His second phone does the same thing!! Does anyone know if this is just a Musiq issue or if there is a way to fix it?