Get an iPhone from the Apple Store for Virgin Mobile?

My power button has been jammed and I wanna go to the Apple Store to replace it with a new phone but I was wondering, would they do it for a Virgin Mobile phone? I purchased it from Best Buy but they don't sell the iPhone for Virgin Mobile anymore. VM has only had the iPhone for less than a year. Should I go to the Apple Store or just contact Virgin Mobile for a replacement?

Contact VM.