I was in a rush to pick it up so I didn't go into detail with them to find out if it's the aircon or fuel; they just said they're ordering a new pipe. Apparently it's the VW reccommended fix as new cars are being manufactured with a different pipe, so might be worth asking if you can get a replacement rather than just having them bend the pipes. I'll post a decent description of what they replace when I get it fixed.

FYI: The rattle I'm getting is the one people have mentioned when the car is warm and you're accelerating from a still start or driving up a hill. It's behind the drivers side of the dash and is getting louder as the weeks go on No issues with changing gear.