Headlight range dial not working?

[quietbullfinch]

Hi all,

My car recently failed its MOT due to the headlight adjuster dial in the dashboard not working. I don't tow and have never needed to use it.
A couple of mechanics have failed to find a cause, but as they don't have wiring diagrams it seems they could only run a few basic diagnostics on it.
It's under a used approved warranty and is booked in with a main dealer in about 10 days. I'm wondering if anyone has had or known others to have this problem?
There is a very occasional noise from the passenger side headlamp, but no movement of the lights. I'm a bit worried Skoda will say both headlight units will need replacing and it won't be covered, as I see the units are very expensive.