iphone 6 plus sound not working

Hey, so I just got a new iPhone 6 Plus though Best Buy. Yesterday, I had it connected to blue tooth in my car and it showed that it was playing music, but no sound was coming through. I had that problem with my old iPhone 5s, so I hard reset my phone and it started working again. It went out again about an hour later and I just decided to wait until I got home to fix it. Then, while I was playing a game, the background music wasn't playing and instead a loud static-like buzzing sound came though. I thought it was the game because a different game's sound worked just fine. This morning, when my alarm went off I got the same loud buzzing sound. I checked the game and my music and both were not working properly either. After I hard reset the phone, the sound went back to normal again. Earlier today, the sound went back to the buzzing. After turning the phone off and back on, it was normal.

Has anyone else had this problem? Is there a way to fix it or should I contact Best Buy for a replacement phone?