Our plumber mixed up the tap plate for the shower with the one for the bath so there was no way you could turn on the water for the bath - the knob was missing (when he went home).
The electrician forgot to wire up the room thermostats to the mains.
(he didn't understand what he had done wrong until I ran some temporary wires over the Christmas holidays to get it working).
He also wired up all the apartment door bells together - which was quite funny the first time someone called around but got to you after a couple of months (he couldn't understand how to fix it).
Someone else put in the heated towel rails the wrong way around so the open ends through which you feed the towels were against the wall.
The gardener's mate, whilst scattering grass seed through it all over the flowerbeds by mistake (I saw her do it) but she missed the lawn.
The person who installed the washing machine said the door couldn't be changed around so it opened against the wall and you couldn't get any clothes in (a five minute job that evening for me but they charged 300CHF).
I'm not too impressed by this Swiss quality either and when something breaks in the house, even my Swiss wife rolls her eyes and mutters "Schweizer Qualität".