Not receiving code to complete Lebara set up

Receiving phone calls and texts now with the sim inside. Phone is also still running on three on the number I’d like to port but when I complete details on the leaves app I am not receiving the code to go through to the next stage

My friend is trying to register new SIM card but UK flag is only showing a single 4 instead of 44 and although putting in the Lebara phone number and message saying SMS sent, no text is being received with the verification code. So registration can't be completed.