Hmmm, well it might be worth me at least sending the dealer an email/letter to have a moan, i might try ringing VW HQ too, though i have a suspicion the dealer will respond that it is standard practice on T&D,
Take it further. Like I said, Quantum oils are NOT approved for VW (and Audi, Seat and Å koda) official franchised workshops.
And pre-2009, the 'standard practice' was to use a 502.00 oil, but that oil MUST be either a 'genuine'
Volkswagen Original Teile® branded oil, or an official 'top-line' oil from Castrol/Fuchs/Shell. Look at this post to see the difference between genuine VW oil and aftermarket Quantum oil -
http://www.golfgtiforum.co.uk/index.php?topic=95565 - so for the pre-2009 T&D, they should have used oil begining with "G 052 167 **".
I'm quite surprised they are using non approved oils as they generally seem to be quite good in most repsects. is the Sytha not actually a VW approved oil then? i could use that as an argument.
Quantum oils generally are very good oils, and they are actually made by Castrol for Volkswagen UK. But nip across to Germany, and I doubt you could buy Quantum - because it isn't listed in ETKA. The part numbers are a dead-giveaway - Quantum oils have the prefix "ZGB" - and Z simply means "non-standard or non-OEM" part, and you can work out what GB means!

Regarding Quantum 'approvals' - well the bottle may say they meet certain VW standards, but they aint approved by VW Germany. To prove my point, log onto this site -
https://erWin.Volkswagen.com - you will then need to set up a free account, and then download the approved oils PDFs - you will NOT find any Quantum oils on there.
Actually, you WILL find a Quantum oil on there (shocked, as I thought none had been approved) - but for the 502.00 standard (the min. spec for the GTI on T&D) - then ONLY the Quantum PD Diesel is approved. Synta Gold is definately NOT approved - so your stealer has fcuked up on two issues!
Worst case, in 10k/ 1 year do you think it poses a risk? She's always had longlife before, i guess i could by some longlife and either change it myself or have a cheaper specialst change it if it is likely to cause damge, there's 48k on the clock,
The Synta Gold wants dumping out the sump ASAP - how you do this is up to you - but I would be adamantly demanding the stealer does it, and picks up the tab. OK, the stealer may want you to pay the difference between the cost of 4.6 litres of Synta Gold against the same of genuine LongLife3 (which will be about a tenner) - but they can't shaft you with labour charges, as they fcuked up!