Seems that the O2 network (which includes Tesco) are having a few problems today, thousands of people complaining because they can't access one thing or another.
It certainly brings home just how fallible these things are, one bad piece of equipment, cable, switch or whatever can disrupt the lives of so many . . .
Obviously some users have genuine problems due to this issue, but I guess most are just annoyed they can't access facebook while on the bus to town