How much did they charge? If it was a couple of hundred then you got the filter changed as well but that is usually done at 30K although @ 15k is a good idea. Changing the filter and refilling would be about the same as you describe. You should also have the TOD/tranfer case drained and filled with the same fluid. Diffs are also due at 15K.

BTW, workshop CD along with another 500mb of VX parts lists, pics and movies is included with every order from me.