i can not receive or make calls

Hi IanFaulc_618833 👋
If this is because of the 3G turn-off (which has happened recently and you are in the Midlands) then just search 'VoLTE' and you will see many, MANY posts with regards to this problem. It may be that your device isn't supported by SMARTY and if so you may have to change to a provider that does, unless you can afford to purchase a SMARTY supported phone to stay with them. 
https://help.smarty.co.uk/en/articles/8985136-checking-if-your-device-is-4g-volte-compatible
If this is not the case then please add extra info so someone can help you further x