Booked a tour with Viator that is already unavailable for the specified date. Thought that the confirmation email with the voucher is valid. After booking the flight, an email from Viator came and was told that the tour is not available on the specified date . Called the telephone number given which was directed to the call centre. There was nothing they could do because there were no more suppliers for that tour on the dates specified. Can't cancel my flight after booking. Huge disappointment to my son and we have to incur unnecessary travel costs. Would not have booked the flight if the tour was not available. Viator Website is not updated promptly and availability of places are not indicated in the website. Viator is unreliable and cannot be trusted.