Why are some of my guests even able to cancel a 'much cheaper no cancellation' fee they have booked

Hi Richard

First link the property so we are not going in blind to this. Thanks

And put it in your partner profile too.

Click my name to see my how to guide

You have that 24h free cancelation active probably. Have those cancelations happened soon after the booking was made?

If so, that is the answer. Booking.com activated this some time ago for all and you have to "turn it off" manually if you don't want this option.

if you link your property like I asked, we will be able to see it and know straight away, instead of maybe's.  thank you kindly