Hi Android,
I would advise calling customer services from a landline (if possible) on 0844 809 0202 or alternatively you can chat to our customer service team online to discuss the issue with them, they may be able to give you a timescale of when this is likely to be resolved if it is a known issue.
Also, try switching the 3G off on your phone, as if it is a 3G mast that is down, your phone still may work on the 2G network (thus allowing you to make phonecalls and texts, at least.)
I work for o2 however my opinions expressed here are my own and not in any way reflective of O2/Telefonica and should not be taken as such. My activity here is to try to help whenever possible.
