Hi stukirby, thanks for your post.
Sorry to hear you've had some problems with your new SIM.
Is this a new number you have recently signed up for, or a replacement for an existing SIM you already had with us?
Is it just data and internet-related functions you're having issues with - do normal calls/texts seem to be working OK?
If you haven't already please try a manual network search via the handset's settings and let us know which networks are showing as available.
Tom