This vehicle was a C200K. The complaint was that the system worked intermittently.

The way it was playing up was that the system may work for a few days and then not at all for a week or so. It then got to the stage where it stopped working for a few months.

The day it was booked in for repairs, it started to work again (so the booking was cancelled) . The A/C was okay for a few weeks. The owner booked it in again and sure enough it started to work on the day.