Thank you for your Update.
Check with Customer Services via 191 or Live Chat just to check your Account is ok.
Can you try your Sim Card in another phone as a process of elimination to rule out the phone or sim card that may be at fault.
If your SIM card in another phone works as it should then by process of elimination it could be the phone that's failing.
Ensure its on the latest firmware.
A Factory Reset / Hard Reset is known to help a phone that's glitching especially after a recent firmware update. You should be able to Factory Reset within the phones settings or Google Hard Reset for your model of phone.
* This process deletes data in the phones memory so please perform a Back up first and move any data possible to a SD Card and remove the SD Card before carrying out a Reset (Handset Dependent)
If the SIM card is presenting the same issues in another phone then I would suggest visiting a Vodafone Store to ask for a Sim Swap which replaces the Sim Card.
If the phone does not remedy after the Reset and the Sim card is working as it should in another mobile phone,then an option is to approach the Manufacturer under the Warranty if it's covered. And the phone has not been dropped or had water ingression as Manufacturers Warranty does not typically cover for issues caused by these.
HTC give a 24 month warranty. Speak to them via their U.K. Support
Vodafone also offer support Here
If not covered under the Manufacturer Warranty then perhaps look to Home Insurance, Vodafone Insurance and some Bank Accounts give Mobile Phone Cover too.
T&C and Excess Fee's need to be checked.
Current Phone >
Samsung Galaxy s²³ Ultra 512gb Phantom Black.
