I always have a problem believing what garages do on the sheduled servicing ...so i usually do the servicing myself.
Even one of the main dealers here was recently in court for falsifying a servicing record ( the owner had marked the filter etc.)That was on a Toyota!!!!
Anyway I was suprised at the amount of crud on the magnetic plug in the diff.Possibly this is why the servicing interval on this item is only 20,000 miles.
It might be prudent to make sure this item is done on your main service!!!!