I've just got my car back from Arnold Clark (Fiat). On the service invoice there are two entries of Filtering Element £10.59 with identical part number (I0055192012). I'm assuming they haven't fitted two of these!?!
That reminds me, I got charged for antifreeze (£3 x 2), I'm not sure how much one unit of antifreeze is but I'm sure it was at the right level when I went in. I'm pretty sure they broke my reverse light too.
The car was picked up and dropped off to my house so I didn't see the invoice until I'd already paid over the phone. I guess I'll be calling them, again.