Originally Posted by rcspeirs

"Very ticked off about the situation and considering disputing the final bill."
My experience is that as soon as you've driven away with the alternative vehicle your negotiating power to dispute the charge is almost nil. Also be aware that the Mercedes comes in lots of trim levels, from luxurious to very basic and "plasticky". I know because I ended up with a basic and plastiky one recently - it was pretty unpleasant.