It hasn't been working for me for over a week now. I get the following message:
The System has encountered an error, if you can not progress your order please call free phone 0870 225 7879 to complete your order. We apologise for the inconvenience and we are attempting to rectify the problem as soon as possible.
Obviously, as I'm not trying to order anything there is no point me phoning their shop up and asking them...
I used to be a Geniemobile customer, and so I emailed them at
e-care@genie.co.uk to ask what was going on, and got an autoreply back saying that email address was no longer valid. I then tried
e-care@o2.co.uk, and got the same auto reply. It seems that either their email systems are down, or they have changed the customer care email without notifying their customers.

I also tried using the email form to send my problem, but surprise surprise, that just brought up an error message too. I'm glad to know that I'm not the only person having problems with the service, but also contacting O2 to get them to sort it.
According to my contract I am "entitled to the quality of Service generally provided by a
competent mobile telecommunications provider exercising reasonable skill and care." I don't feel that I'm getting that at all, therefore putting them in breach of contract. Unfortunately, for me to get them to do anything about that, I have to notify them, which of course I can't do... I'm getting seriously unimpressed with them.