I had a similar issue with my Touareg at first the front drivers seat started creaking and got it very annoying,the dealer tried to fob me off because the 10 stone supposed master Tec could not hear it until i took him out for a test drive and it creaked loudly when your weight shifted from left to right.
Dealer then changed the cage on the base of the seat and fault was cured,6 months later passengers side did the same and despite telling them what the problem was i went through the same hassle until they changed that one and now both seats are quiet.
The noise was very a loud creak and not the type of rattle/creak you would ignore, maybe the same problem with yours ? spare parts cost £400 each and was done under warranty so that is maybe why they were not keen on changing them as they would have to justify the parts cost ,not my problem i kindly explained