No stars would be my actual choice. I tried to upgrade, cut off after agreeing a contract price. Got a call back agreed a price confirmed (with Blue Light discount) went to make the upfront payment - again cut-off, this time no call back. So, I had to ring back only to speak with a different advisor, who gave me a higher price - telling me that I could not have been offered my original price (easily confirmed by listening to the call recording - that I asked to be checked). I have been an O2 customer in its various incarnations with 2 accounts for 31 years and have never experienced such shoddy customer service or ever been called a liar. I could not speak to a manager and when I asked for customer concerns I was thanked for choosing O2 (not sure if that was sarcasm) and passed not to customer concerns, but to another customer service advisor who asked me to verify my account, again, as I had been transferred without information and that it would take up to 48 hours to get a call back to discuss my complaint. I then get an email a few hours later which had the Pre-Contract Agreement generated from my first call, that I was told never happened!! One-and-a-half hours wasted and being accused of uttering falsehoods to boot. O2 should be reported to the Advertising Standards Agency for misrepresenting customers by stating they have customer service.