HTC ONE M8 No notifications or texts coming through or sending on o2

[AC Question]

Had this phone for under a month and instantly had issues. At first, it crashed every day.. i did a complete reset of my phone and its made it worse. I have dead pixels in one spot and now suddenly after it crashed again no texts come through/send and notifications dont work. i did the usual off and on but no difference. My notifications are on and so id my wifi but no facebook messages or texts come through. Any ideas because im going to carphone warehouse on saturday to kick up s**t