I just recently (6months ago) switched preferred airline to Northwest. In using the Worldperks, do you find them responsive to requests and letters? I came from American, as a gold member and ran up like 20,000 flown miles from Sept to the end of the year on NWA. I wrote them a letter detailing my change and asked if I could be upgraded to next level of their program on a trial baes (all other airlines do this). Since I only missed the target mileage by such a small amount and with my change in loyalty, and my extensive travel plans for the year. They did not even acknowledge the letter. I am wondering how they treat their preferred customers?