Thank you for this review. The problems comes from yourself. That means, normally, after the breakfast you are shown the way to the "Skip The Line Entrance" of the Breakfast customers of Restaurant Ore Ducasse. So it seems like you were not following the instructor who showed the way to go skip the line and got lost. Then you have find yourself in regular entrance line. Which means you've been out of the restaurant and gone to the regular entrance line. This is not our mistake.
Your voucher about which you talk about from Viator is not an entrance ticket. It is only a document to prove your purchase from Viator. Thats why we send you your tickets by e-mail or you redeem it from Restaurant Ore Ducasse. All this informations and details about the visit are given to you by e-mail. It is all explained in your voucher too.
For the next time you book just be careful what product you book, DO NOT IGNORE to read all the instructions in your voucher and please remind to check your emails about your booking.
This way you will have a much more comfortable visits.