Good Morning @kismet_anya, thanks for coming back to us
Are you able to check the SMS centre number is +447458 399008 for me?
To do this;
-Open up your text messages on your phone
-Select the three dots in the top right hand corner
-Settings
-More Settings
-Text Messages
-This will then show the Message Centre number.
If it matches the one above then everything should be in place to send a text message.
If not, please manually update this, save it and reboot the handset
Kindest regards,
David_Bn