Amazing network, sad to leave.
I've never, ever had any trouble whatsoever with O2, was a pay and go customer for four years and the only reason I ever left the network was because the signal coverage for where I had moved to was poor. Something which O2 told me they'd look into when I told them I was leaving, no pressure from the salesmen on the phone who simply wished me luck and thanked me for my custom. I can always understand what the customer service representatives are saying and they are always helpful! Apart from my current location I have also never had any trouble with their coverage, signal strength and internet alike.