I was recently in Italy, and my PlusNET SIM would only give me 3G, never 4G. I was with 3 others who are with PlusNET, all received 4G, all on the same local network as me. It didn't appear to be related to the phone, only the SIM. (And I receive 4G in the UK fine). It wasn't a big deal this time, but I'm concerned my SIM may not give me 4G if I go abroad in future. Any suggestions for how I go about getting this checked / fixed, please?