Hello. So yesterday I bought a used Galaxy S3 for 200 dollars. It looks brand new, it has no scratches or anything. Originally it was an at&t phone but it was unlocked so I connected it to MetroPCS. All I had to do was pay for the Sim Card and Number Transfer. The thing is that its stuck on E or Edge instead of 4G. Can someone help me out with this? Thanks in Advance.