I have a double booking and need to cancel this one as the calendars never synced

Hello!

Very sorry to hear about your double bookings…

Please have in mind that sync is not in real time and double bookings can occur…

Since this is only a Partner Community you have contact booking.com if you need support…

Wish you all the best…

Thttps://partner.booking.com/en-gb/help/guides/how-better-understand-prevent-and-reduce-your-cancellations

This link might help you…