1) Permanently Bar and Replace: Use this option if you have definitely lost your phone and / or SIM.
Your sim will be permanently barred with immediate effect meaning no-one will be able to use it. You also have the option to bar your phone, this means that your handset will be put on a national blacklist and no-one will be able to use it. If you bar your phone you can undo it by contacting an agent here, a permanent sim bar cannot be undone. A replacement sim with your full balance and phone number already tied to it
Head here to report your SIM and/or phone as missing.