Plugin needed with reservation and reducing capacity

[ Moderator note: moved to Fixing WordPress. ]

Hello,
I have tested a lot of booking plugins like Booking Calender, WP booking calender etc. There are great, but they are all based upon the concept of making appointments in a time slot for 1to1 meetings per day. Other plugins deal with hotels and restaurants for rooms or tables.
But none of them have what I need. And it is so simple.

I give workshops. I just wat to have a reservation system with a maximum of capacity (number of persons) per day. No time slots per hour.

So my customers can see the days that are available (green color or whatever) and they sign up for one day. If they have booked the workshop , the day should be red and not bookable if the maximum is reached.
I give workshops and want a maximum per day. Which plugin has this feature?
If they have booked one day, they may not be able to book another day.