Two emails to the DM service center were met with wrong information. I purchased two tickets on Jan 23 (within the qualifying window), but was told that I was no eligible because they were purchased on March 31. After talking to a VERY helpful person at the DM service center (by phone), I learned that since there was a schedule changed, my tickets were actually rebooked automatically on March 31 and so they no longer "appeared" to be eligible for the promotion. She apologized, credited the miles while I was on the phone, and asked for the name of the person who had replied incorrectly to my email request so that she could "educate" him.