Update : this booking was made via the tripadvisor website- I had no idea Viator were involved until the tickets arrived.Tripadvisor can't just hide behind 3rd party responsibility...Booked a trip... nearly 300usd.Get an email from the tour provider an hour later apologising - stating they are fully booked and have no availability.Request refund via site.. informed via Viator (secondary party who issued 'tickets') that the tickets were non refundable! Despite the tickets being for a non existent service as the tour operator refused to provide it.What a complete and utter joke - how can these clowns claim to be running a business?Eventually got a refund after complaining lots via social and direct customer service chsnnelsIt's an absolute joke that this company holds itself out as a credible source of travel information if they're going to subsequently offer such shoddy service on a sell through basis