O2 post this apology on their blog:
We would like to apologise for the service disruption some of our customers have been experiencing since yesterday afternoon.
18/07 14:35: update
As we said in our last update, we want to make it up to our customers for the loss of service some people experienced last week.
The issue we had was unprecedented and we recognise that this caused inconvenience and frustration to those impacted over that one-day period.
We have now identified all those customers directly affected (those whose devices could not connect on our system) and we and are giving them the equivalent of three days back for the disruption as a gesture of goodwill and to say sorry.
- Pay Monthly customers will receive 10% off their July subscription which will be applied on their September bill, which is equivalent to 3 days back
- Pay & Go customers will receive 10% extra on their first top-up in September
To thank all our customers for supporting us through an unprecedented and difficult period, we are also giving everyone on O2 a £10 O2 voucher to spend in store. This will be redeemable via the O2 Priority Moments app or online at www.o2.co.uk/priority. It will be available between 1st and 30th September to download through Priority Moments and use in store, with no minimum spend. (One voucher can be used per transaction and no change given.)
We will contact all O2 consumer customers and those small businesses with fewer than 10 connections by the end of the day on Friday 27th July giving full details. This will be by text message. Other business customers will receive communications through their account managers or our channel partners in the coming days giving full details.