S20+ Can't make calls, have to keep restarting phone

[Rondeco]

Hi All,

I have an S20+ and I keep having to restart it at least once a day to be able to make any calls, if I make a call I get the 'calling' screen but it never actually dials out until I reboot it. 

I've tried clearing various caches and given it a hard restart but still the same.

Any ideas what it might be?

T.I.A.

Ron

[MI5]

@Rondeco 

First thing to try would be a new sim card, it's free.

Pop into your local store, if open, or you need to contact O2.
All numbers are in this guide Guide: Coronavirus Community Help and Support 
Or 202 from your O2 mobile.
Advice from an O2 Guru to get through:
When you call 202, you will be asked for the reason you are calling.
Stay silent for 15 seconds and you will be taken to the keypad options.
Press 2 for Everything Else
Press 5 for More Options
Press 7 for Anything Else which will put you though to someone.
You can also try saying "Upgrade" or "Fraud" to be connected to an advisor.