Bunk beds

A bunk bed gets delivered at just after 6:00. I then spend much of the day assembling it. Well built, sturdy, but with what seems like an obvious flaw.

The top bunk is clearly marked with a line that says “Mattress must not be above this line”, but the mattresses they supply are over 5cm above the line. When I ask them about this, they casually say “that might seem like a problem, but the mattress will go below the line when someone is on it.” It doesn’t. This is not the end of the matter :(