I have a Samsang Vibrant T959 4G & every time I turn on the WiFi, I lose my phone signal. I can't call or text & I have to restart my phone all the time. I don't think it's my SIM card cuz it worked fine a couple of days ago BEFORE I switched to this phone. Also yesterday, I went to Schlitterbahn & turned my phone off & left it in the car. When I turned it back on, it took me 3 hours to gain signal. Should I return this phone?