Question for the OP: Are you the original owner of the car? If not, perhaps they were changed some time ago and that is why the SA is telling they are not due for a change.
Like others, mine were changed at 23,000 miles as part of a regular service visit...
2011 Space Grey E90 M3, DCT, Comp. Pkg.
1997 Z3 2.8, Artic Silver, Tanin Red interior, MT
1974 2002tii, Inka, 5 sp manual