I wonder if anyone can help, my husband has a Samsung A3 mobile phone which I bought him for Christmas last year. He upgraded his tariff with O2 and got a new sim. However I have just discovered that he has never had 4G on his phone. Yesterday he went to the O2 shop and they changed his sim card again. However he still cannot connect to 4G and the only option is Auto 2G/3G or 2G or 3G. It's very puzzling and any advice would be very welcome. It is a 4G phone as my daughter has the same model and has no problem.