Mine has just started slipping in 6th. Luckily I'm a mechanic so I can do it myself still annoying though. Any good garage should have a
guide for movement allowance in the flywheel. Mind out as most garages say it needs a flywheel just to get a extra sale. Been a mechanic for 2 years now done about 30 vw clutchs and only ever fitted about 2 flywheels. We keep all the parts we have replaced for the customer to see so ask for them to keep it and I'll get the movement numbers up so you can personally check it and make sure you haven't been done!