It's a bit of a strange one? @Anonymous Please let us know how this turns out or if you have any further questions.
→ COVID-19 support - Help and support from O2 during the lockdown
→ Access for You: Registration - Find out how to register for our Access for You service.
→ Just joined the community or thinking of registering? Check out this handy starter guide!
→ Have a query about your account? See if the My O2 how-to guide will help
If you'd like to take part, why not register? 
Glad you finally sorted it out which is why I suggested trying the sim in another phone. That would have confirmed the phone was ok.
Awesome glad to hear this was sorted @Anonymous!
→ COVID-19 support - Help and support from O2 during the lockdown
→ Access for You: Registration - Find out how to register for our Access for You service.
→ Just joined the community or thinking of registering? Check out this handy starter guide!
→ Have a query about your account? See if the My O2 how-to guide will help
If you'd like to take part, why not register?
Try cleaning the sim card. Reboot the phone. What have you tried? Is your account up to date with payment?
Another one!
All sent to confuse...though it is Friday night 
