I stopped supporting them a few years ago. We went to visit a local National Trust property and there was someone buying tickets, two ladies behind the counter so I stood next to the customer, 2nd lady behind the counter ignored us. Another couple came and stood behind the first customer, as he left they were served. I though meh she probably thought other lady was serving us. With both previous customers she gave them the tickets a brochure and came round the counter to point out points of interest. She then started to serve a third couple, I said, "Am I invisible" she ignored me. The couple said, "these people are in front of us." She served with little grace, shoved the tickets across the counter, no brochure, no effort to point anything out.
I don't know why she did it but suspect the colour of my husband's skin was the main factor but I can't prove it but I will never go in their properties again. So yes I am happy if they want to punish bigots.