Ive been looking at Audi, Skoda, VW forums regarding Haldex servicing. There is a range of service intervals for these various cars but 3 years /30K miles seems to be the most frequent. Apparently the Golf R service interval was reduced to 20K miles (presumably gets a lot of wear on account of its stunning performance).

So I'll get on and change my haldex filter and oil as soon as I find time and before the weather gets too cold. Jules

I serviced my Haldex at 110k and 10 years of age. The filter was showing early signs of blockage. The job itself wasn’t to bad. Getting the prop off seemed to be the biggest struggle! Alot on here seem to shy away from doing it by themselves, but really would advise the semiskilled DIY mechanic not to shy away from just follow instructions in the manual which can be found on here somewhere.