I would also contact VW and see what they say, if you tell them that your dealer is giving you nonsense excuses, they will do something about it for you, or at least they should.
I agree with aw1m, the leather must be defective in some way. 12st is in no way fat, I was just double checking you were not 25 stone or something lol.
p.s. If anyone is 25 stone, I'm not sorry, so stop f**kin eating.