What I did was go to www.spg.com, it took me to Marriott.com and to my Marriott account, as that was my last login, only asking for my password. I then signed out (not just close the window as I used to). Then when going back to login, I was presented with a request for my username/email address. That's where using your old SPG number and password should present your new number and let you in. Another technique is to go to the login screen and click on Clear Remembered User to be presented with a request for username. If that doesn't work, then a call seems to be the only choice left. Good Luck.