A reservation request got auto approved despite the settings being against this.

[Uta8]

How do I undo this approval. I have left a message for the person who made the booking. How do I call airbnb?

[Emiel1]

See: Contact Airbnb - A Community Help Guide [UPDATED]

[Marit-Anne0]

@Uta8 

As far as I can see you have Instant Book activated - I am able to book your place here and now.  Better check your settings asap.

[Marzena4]

And check what penalties for cancellations. In this case you might excuse yourself with that Instant Book being on.