Trusted contacts is a really interesting idea, and we’ve been discussing how it could work internally. As you mentioned, if you don’t have access to your phone to freeze your account, you could ask a trusted contact to do this for you.
We could take this idea even further and use it during device verification. Upon opening a Monzo account, we could ask you to nominate a number of trusted contacts (if you wish to opt in, of course).
Then, if you replace a lost or stolen device (so we can’t use your old device to verify your new device), and are away from any forms of ID, we could use a trusted contact to help us verify that it is indeed you who is trying to sign in on a new device. In this situation, your friends and family would be better at verifying that this is actually you. Until you do this we would limit account functionality, for example we could block large payments until verification is complete.
These are just some thoughts on how such a feature could work, but I’m interested to hear if this is something you would feel comfortable using?