I got my first mobile phone when I was 18.
I'm 40 now.
My first phone was pay as you go with O2.
My current phone is pay as you go with O2.
That's 22 years of being an O2 customer.
I've had a couple of contract phones in between but I've always had a SIM card with O2.
I've also got a contract with 3 right now but I haven't got a clue what the phone number is, I'm with that purely because of having unlimited internet on it just in case our home Wi-Fi goes down or I'm taken into hospital again. If O2 offered unlimited internet I'd pay the rest of my contract with 3 and immediately set up a contract with O2.
There's nothing at all wrong with 3, I just know how things work with O2 and like their rewards is all.