So I've experienced something similar minus the overcrowded room with British immigration. I watched the immigration official turn from apathy the moment I handed my passport over into passive agression with loaded questions ("When was the last time you were deported?" answer: "never") into apologies ("Sorry for making you wait sir there clearly has been a misunderstanding") to vague answers to the question of future prevention.

After being told "and there's nothing you can do to stop this happening again", I tell every British immigration official I stand before briefly what happens every time I want to come back here and they're usually understanding about it all.