Hi.
It can take upto approx 24 hours for all your services to settle after a Sim Swap. This procedure moves your existing Tariff and original mobile number to your new SIM card.
Sim swap link :
http://swapmysim.o2.co.ukTurn your phone off and on throughout this period helps.
If it has not activated after that then remove your sim and wipe it. Re insert and turn the phone on.
Check your Apn settings.
They should be ok but it can't harm to check.
http://www.geeksquad.co.uk/articles/chapter/595-04-how-to-set-apn-settings-for-the-02-mobile-networkAfter that ring O2 on 202 to have your account reset.
Here's a help link from the forum about connecting to Data Services.
Credits to Forum Member @jonsie
http://community.o2.co.uk/t5/Android-Devices-Samsung-HTC-Sony/Connecting-Android-Phone-to-Data-Servi...