You could also get the Monzo app on another phone, log in and then freeze your card. If you have a friend who uses Monzo, they can log out of their account, let you log in and freeze, and then get them logged back in.
You could also get the Monzo app on another phone, log in and then freeze your card. If you have a friend who uses Monzo, they can log out of their account, let you log in and freeze, and then get them logged back in.