Disappointed

I have a voucher that is expiring on the 22nd of December. I have been trying to book for the past 2 weeks. Their phone is always busy or it rings and no one answers. Finally they responded to my email and told me that they are fully booked and they will have space on the 19th onwards. When I called and emailed to make a booking they told me that they are fully booked for the 19th and they said they have space for the 21st and that I must send them a WhatsApp with my voucher and details as their email address is not working. I have sent them what they require but I got no response from them to confirm my booking is in place. Their communication and service is really poor. Really disappointed.