On December 31, 1999, Microsoft Product Support Services were ready in case something horrible happened as the calendar rolled over into the new year.
I'm told that Microsoft Press also had its own Year 2000 plan. They staffed their helpline continuously from Friday evening December 31, 1999 all the way through Sunday, January 2, 2000. They did this even though Microsoft Press did not normally staff its helpline ouside normal business hours, and even though all sample code in all publications come with a disclaimer that they are provided "as is" with no warranty.
I do not know if they took any calls, but I suspect not.