Stuff happens. Since you don't want to upset the owners, I would recommend that you just let it go.
The owners had to make the selection to disappoint one person or a whole group, who may end up as repeat customers. Or conversely they only have you telling us about your disappointment, where as if they honored your request, they would have a whole bunch of people telling us how disappointed they are. And as a side note, the group was there with cash and you were just a promise.
I understand your disappointment, but if you think about it, you may have done the same thing to someone else.