Very very poor. I was migrated over from Virgin mobile where I was on a £0 contact. I was automatically passed to o2 and charged £25 even though I didn't use the new o2 account and I wasn't advised that my new account would be charged at £25 per month. When I tried to dispute this, I was advised I couldn't put a dispute through as I didn't make am attempt to pay. So they charge me without notifying me and then say that I can't dispute it because I didn't pay for something I didn't know I had to pay.... It's almost laughable!!