o2 Network Shops are open everyday in my local Uk city centre so yours should be too @janeybobs
Give o2 a call or use their Live Chat to have your account checked.
Check your settings in your o2 App.
Try a soft reboot by turning the phone Off and On.
If that does not help then go into Settings, General Management, Reset, Reset Network Settings.
As a process of elimination try your sim card in another phone if you can.
I wish you all the best.
Daily Driver > Samsung Galaxy s²² Ultra 256Gb in Phantom Black.
The advice I offer is my own and does not represent Samsung’s position.
I have no affiliation with Samsung.