I've been with O2 for almost 5 years now. I swapped to them as I got a much cheaper deal for the same package and have been with them ever since. My monthly bill has only gone up once during this time, due to inflation and is still really reasonable. I never have any issues with the network, I get excellent service, even when I'm visiting my parents in the middle of the country side! Their customer service is brilliant, in store, online and via call centre. Any queries have been dealt with quickly and professionally. Handset's are normally very reasonably priced and they are very willing to work with you to find a deal that suits you. Most of my family is with O2 due to their reasonable prices and excellent network service. The O2 reward app is also brilliant as you get freebies throughout the year, early access to events and competitions.