O2 are crap with data allowances...
Can I ask what you define as crap Al?
I've been with O2 since the eighties, I have tried other networks in between but for the last 14 years it's been O2 for me.
I currently pay £12 per month (inc) for 600 anytime, any network minutes, unlimited SMS, 20 MMS, and 750MB of data.
Even with my current hospital visits where I'm tethered to the lappy using the net for the entire 4 hour stay I still don't hit my data limit, and I'm not that sociable so I don't get anywhere near my talktime.
Another plain advantage in my eyes is that if I do have to call customer services (a very rare occasion), I get to talk to someone in Leeds rather than someone based over 5000 miles away whose 3rd language barely comes close to English.
That is worth £12 per month inc any day of the week in my eyes IMHO.
Anyway, back to the OP.....
My mate is on O2 and so am I, his phone signal/connectivity was at best erratic this afternoon, mine was fine as I was making and receiving calls while his phone was down.
I guess O2 are having a repeat performance of handset registration issues based on the fact we were sat next to each other in the same pub when this was happening.