No internet when on mobile data

[Twiglet1]

For several weeks I’ve not been able to use mobile data although phone says I’m on 4G. 
I’ve tried resetting network settings several times.

3 have sent me a replacement SIM card but this has made no difference.

I’ve got an iPhone 11. Any ideas/help please !!

[PeteG]

Hello, Twiglet1.

Welcome to the Three Community. 

Gosh, it sounds like you've already taken some of the steps we'd normally expect to fix an issue like that. 

Can you confirm if the internet works fine on Wi-fi? Can you also let me know what is happening when you try to open a web page? 

Pete.