They are defiently taking you for a fool sorry to say, YOU need to stand your place, they have obtained money by deception in the fact you have paid for a service you haven't/are not receiving. I certainly would not have paid the money!

Have you got it in writing?

It certainly would not cost £390 either, at the end of the day it's an electric window (most expensive part is likely to be the motor!)

Basically you need to verify the motor is getting power when switched and it actually works, and also check the regulator and the switch is ok.

I presume this isn't a Ford dealer? In any case name and shame!

Martin