@Fran123It could be a variety of issues:
1. Try you sim card in a different phone and see if you have the same issue, if not it could be a phone issue.
2. Have a look on
https://status.o2.co.uk and enter your post code and see of there are any issues in your area
- Xperia 1V - o2 and Spusu
- Pixel 8 Pro - o2 and Vodafone UK