Have the phone Sony Xperia Z4 mobile. Model No. SOV31... I can access wifi and can send recieve calls and txts but cant access mobile data....?????? have tried all setting such as 2g, 3g, LTE and auto but alwats get '' Not Connected'' message when accessing apps. Also tried turning on and off again a number of times and do get bars but sometime get a small ''x'' about the bars.. No ''x'' at present, only shows signal strength.