I was a Three customer a few years ago (around 2004-2008) and they weren't very good. Bad reception, bad customer service, bad handset choice etc. So I was actually quite reluctant to use their service this time round.
My contract with one of the other networks ended in April 2012, and I wanted to get a new contract on the iPhone. Three were the only company offering unlimited data plans (including tethering which most networks don't seem to offer for free) which is what I needed. As well as this, it was actually the cheapest iPhone contract available for what you were getting (The One Plan with 2000 minutes, 5000 texts and tethering included - all for £34 p.m. + £49 for the phone).
Due to my reservations, I asked around and seemed to get mixed reviews regarding moving to Three. To deal with the potential reception issue, I got a free PAYG sim to test reception at home, at work and along my usual routes - it was about as good as I was getting on all other networks.
I then decided to go ahead with my purchase. It was actually surprisingly simple on the website (a huge improvement on the old layout). The only downside was that it doesn't let you complete the purchase, and instead tells you that there has been a problem with your order (hence -1 star). A friend had told me that this happened to him as well, so I went ahead and phoned customer support. They were quick and helpful and told me they just needed payment for the phone and it was despatched that day.
Since then, the billing has been simple, I haven't received unnecessary calls and texts from customer services...yet (another improvement).
Overall, I am impressed so far.
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