Poor service, refusing to give refund

If there was 0 stars then I would be using that. I used tripadvisor for the first time and booked a tour from Dubai to Abu Dhabi and the tour guide did not show up. I then sent screenshots proving that I tried to contact the guide multiple times and they didn’t answer. However according to viator, this is not sufficient and I am still being charge for something that did not happen. Be very careful when booking on here, they are not as trustworthy as you would think