Ported number but not able to change on iphone

I’ve moved from O2 and ported my number over. All was working fine except I can’t change my number in the settings from the sims original number and now I’ve had a notification from Apple to say the number I am using isn’t connected to my device and therefore states iMessage and FaceTime will no longer work??

You need to disconnect iMessage and reconnect

I had tried that and unfortunately still not working 😣

Try below
Basic Troubleshooting
Restart Phone & Toggle: Turn off iMessage & FaceTime in Settings, restart your iPhone, then turn iMessage & FaceTime back on and wait for activation.
Verify Number in Settings: Go to Settings > Phone > My Number and make sure your correct Lebara number is entered.
Reset Network Settings: Try resetting network settings (Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings).

Oh you beaut!! That toggle worked!!!
Thank you so so much 🥰