I sent the following to the restaurant’s manager, but they never responded, so here it is:

I would like to make you aware on an unpleassant experience that we experienced on Saturday, 11th September with one of your restaurant staff members, which changed our view of your otherwise lovely restaurant. We made a booking for 2 through the National Restaurant Week website, after having previously visited your restaurant multiple times. I also called you in the afternoon of that Saturday to ensure that we are seated outside, because we would visit you with my friend's dog, and you confirmed that indeed we would be seated outside.

When we arived and made the waitress aware of our booking, she said that there were no tables available outside. First of all, she made no effort to check if any of the customers were about to pay and leave the restaurant before responding to us. Furthermore, they should have checked whether any other customers, like ourselves, made bookings outside before accommodating people in tables that were already booked for later in the evening.

What I am really shocked by is the way she treated us and looked down to us, as if we did anything wrong, whilst this was clearly your restaurant's issue. The lady I refer to had black curly heair. There was another really lovely lady who tried to accommodate us after the incident (long black hair tied up), however we explained to her that we were not feeling comfortable and welcome anymore.

It is clearly a loss for your business as we were not a one-time customer, but returning customers, however I thought it is mandatory to make you aware of the incident above.