Hi Michael, I’m sorry to hear that this has happened. Unfortunately there’s not a great deal that we can do to help you solve the issue & the support team will need to look into this.
Did you include the 9 digit number from the bottom of your card as the reference? That enables the team to link the transfer to your account.
The support chat appears to be working to me in the app (the response time is currently under 10 minutes), although I didn’t actually send a message to check, for obvious reasons. So hopefully someone from the team will be in touch soon.
You can also contact the support team by sending @monzo a DM on Twitter or emailing help@monzo.com. If you do use either of those options, I expect it would help if you mention that you sent a message in the chat too.