I have no reason to doubt your side of the story LynchMob, but having said that, I'm sure there are 2 sides to it and I'd be willing to bet part of the problem as your calls went along and time passed was that you became more and more (legitimately) exasperated, thus putting the NW folks you spoke to more and more on the defensive. I say that not as a criticism but more as a comment on human nature (trust me, I've been there myself on your end of the phone).
Where I SUPPORT your post is the issue of whether or not the behavior you described by the NW folks is the exception or the rule. I know that the majority of NW folks I deal with at all levels (in person or via phone) are polite and do the right thing, but there are still enough who don't, due to all the cr*p they've had to (or chosen to) tolerate from their upper mgmt while they watch said mgmt line its personal pockets, that it becomes the overall perception. NW mgmt needs to make it a TOP PRIORITY in re-training its workforce to convey that EVERY customer interaction could be a new customer's first impression of the airline, and there are no do-overs. Poor employee morale and the resultant poor first impressions have cost NW more than its share of would-be repeat customers.