She looks like she has all the toys except Moon Roof. Id haggle on that price mate, see if they will remove the SatNav and do you a deal??.
Looking with what its got, you'll be lucking to get £2500 off, but they wont budge on your trade in if they do. You should find out what dealer forecourt is for yours, then knock off 2k, and thats deemed enough in a part ex to do a deal.
If your cars 18500 on their forecourt they should offer you at least 15k. (depending on your mileage and condition of course) use the other white Ed30 choices as a bartering tool on Vw's website, say your take your money to them instead if they cant. Especially that they are cheaper then the one your offering to buy and your not bothered to travel to see the others.
Watch em squerm!!