Messages aren't sending nor am I reciving messages

[Georgia97]

My messages aren't sending nor am I reciving messages, this has been happening for quite a while now and it happens up to 1-2 times a week or two but what I mean by not sending or reciving it just says sending and it will say it for hours and I won't recieve messages at the same time and then at 4:00am they send and I recieve the messages.
This is starting to get really annoying because I get important messages.
Thanks

[MI5]

You could try getting a new sim card but it's most likely a network issue.
Check your postcode here to see if any work or faults are reported http://status.o2.co.uk/
If not it's likely just congestion due to over capacity on the network.

[jonsie]

A couple of things to check first.

Look for mast problems in your area : Service Status

Try cleaning the sim card and rebooting the phone which should reset the network settings.

Next step would be to replace the simcard at your local o2 store.

[MI5]

I will just add that texts aren't 100% reliable and there is no guarantee that any will be sent.
If it's important info a text should not be relied on alone.