This is a UK landline phone number for Viator: 01224 928241. It is impossible to find on their website.
They do not have a complaints page on the website. This number is almost impossible to obtain, but for pissed off UK customers does seem to work. Please circulate it widely. I will never use them again.
I am still waiting for the refund which they have promised. They booked a tour which never came through apparently because the operator spelt the email address incorrectly. Second attempt: the operator booked the wrong date, realised this and assured me the error would be corrected and I would not be charged twice. Third attempt got the tickets and went to the show.
Got back to UK to find I had been charged twice. It took me 3 hours on the website and various forums to get a working phone number.
Review about: Viator Tour Booking.
Reason of review: Order processing issue.