I've never had a company pre authorize my credit card prior to booking. This company put a hold on my funds, than attempted to book the tour. The tour was full, viator did not inform me of this until 2 hrs beforehand. Trued repeatedly to call them but battery died on my phone while on hold for over 2 hrs... never spoke with anyone. They only respond to customers who leave bad reviews on their own site. No email response from customer service, nobody to answer the phone for customer service... so now trip did not take place and cannot book anything else as they have held my funds for a tour they try to book after the fact. All viator does is book for you and charge a nominal fee for doing so... you can book the tour yourself easily if not easier. If you plan on using viator please please please read all of the reviews from review sites not affiliated with this company, or prior to booking try calling or emailing them to ask a question and you will see the service you get. Good luck if you use these idiots.