When you have a promotion that has a set number of bookings available, when that number has been allocated the promotion should still pop up but have a sold out or allocation exhausted note on it. Currently once the promotion allocation is exhausted it just doesn’t appear which can be confusing to guests as they have booked looking for the promotion and then just book normally adding a note that they want the promo in booking notes which becomes contrary to the whole process of having a promotion with parameters.
This is a very good point on the promotional availability. The idea of a 'Sold out' message is common for ticketing companies to keep users informed of availability and save further enquiry. The problem you have described is that there is often 'Standard availability' on offer and customers are continuing to book.
I will check with our development team, but I believe the structure of the booking widget is to check for availability and promotions and show all availability. I can imagine this would require a change to show all promotions which have sold out and as this wouldn't be appropriate for all customers, would need some form of setting that you can control.
We don't currently have this planned as a widget update but I will keep this in mind and update you if any related development is started.
Thanks very much for the feedback.