I am extremely dissatisfied at Samsung's service. My galaxy S3 periodically powers itself when you put down the down with face down. My phone was unlocked too. After I sent to Samsung for a service, which took almost a month, I found the problem was not fixed, on the top of this, my phone was locked! All they did is that cleaned my phone (from the service paper). I had Galaxy S2 before and had an issue too. I sent it out for service 3 times and they did similar thing - clean, reset my phone.... I am determined that my next phone will not be SAMSUNG!