Order/website problems

Have been trying to order a pair of custom aviators however whenever I go to confirm the payment I keep getting this message.

“The action not allowed either because of a changed state of the object or other reasons, please try to refresh your screen”

I’ve tried clearing my cache, ordering in on a phone and computer, using different cards, and using different browsers however none of it has fixed it. They have a 20% sale on custom sunglasses and I trying to use it before it goes but this website is making really tough for me to want to order.