I dont mind being corrected at all, If I feel strongly enough to debate it more I will, but If I'm wrong I'm wrong and will say so. What does make my blood boil is that mistakes were made by both people, i.e. chassis and xds. Yet my quite rightly corrected mistake was me being 'owned' and the xds mistake was swept under the carpet. How convenient.
His mistake was very minor, yours was epic 
Of course it was, I can see someone new to the world of buying a GTI reading this technical 'owning' persons advice and going to a dealer and giving their spec and having XDS down as an option, dealers says, thats standard. Ah ok says the buyer. Buyer gets his car, XDS is there but was thinking, where's the sport and comfort modes... Dealer, erm thats not XDS thats ACC you never asked for that. Bit of a pisser for the buyer no ?
Horsesh!t. The purchaser should read the official sales brochure and pricelist to verify what the 'acronyms' mean, and what are options and what are standard fitment. Or are you really saying that someone should lash out £25k notes, wholly and utterly based on what some dood on the 'tinternet', whom you don't actually know from Adam - and completely ignore VWs own official printed literature.

Their glossy brochures clearly state what XDS and ACC are. I made a simple mistake of confusing one acronym for another, and it is blatantly clear to see that it was just an unfortunate 'mistake' - yet it 'boils your blood'! Go and smoke a spliff or sommat!
Buyer gives spec of car to dealer, Buyer.. 'the 6 have the same chassis as the 5 ? Dealer, yep it does. Buyer... Cool.
Where's the epicness in that ?
Simples. ACC and XDS are in the brochure, and are easily verifyable. 'Chassis' detail is NOT in the brochure, but IS available from reliable external sources!

Simples number twos. Dub stealers have got to 'big up' in any way they can - so if they can somehow portray that the 6 is a complete new car, then they will.