Well, in my household of 4, (2 adults and 2 teenagers) we have 4 contract phones with Vodafone. I wouldn't use anyone else to be honest. I've never had any major problems with the Vodafones service. If a phone fails, and it's inside a warranty, the phone is replaced without quibble. I found I can get a network signal where most people can't. Cadwell as an example, TP (Orange) had no network, I had a full signal. Concerns with billing are dealt with in a professional manner, upgrading is easy, changing price plans is simple. They have given us a great contract for these phones, and one bill which I access on-line, which breaks down to all 4 phones. I'd suggest online billing over paying for a bill to be posted.
I can personally recommend dealing with Vodafone direct, all the information you need is on their website. I've now been with Vodafone for 7 years. I just wish they sponsored a better football team
PAG phones, expensive to use, okay for emergancy phones. My Mother Inlaw has a PAG phone, and she only uses it once a month to remember how to use it, and yes, it's a Vodafone PAG. But for what she needs a mobile phone for, PAG are value for money.