Why it is not possible to decline booking requests?

Normally, you have the option to decline a booking request by clicking on "Decline booking" within the booking details. 

However, if a customer has activated a booking request that was paid for with a product voucher, you do not have the usual option to decline the booking. This is due to technical reasons. If we allowed the booking request to be rejected, the amount of the refund would be paid to the original purchaser of the voucher. This, of course, is not in the interest of the recipient, who wishes to convert their voucher into an activity or event.

Please offer the customer an alternative date under "Send a message".

If you cannot agree on an alternative date, the booking request must be allowed to expire. After 72 hours, the status of the booking request will change from "Awaiting confirmation" to "Expired". Since the voucher was redeemed by the customer against the original booking request, you now need to create and send your customer a coupon code matching the original value of the coupon. The customer can make a new booking through your ticket shop when they are ready.