At the end of November, I purchased an MJ bag from Bergdorf Goodman. I knew right away I didn't want it so I returned it using their enclosed return form the same day. Stupid me, I didn't keep the stub with the tracking number on it. They have not credited my account and Amex is telling me before I get a credit I need to provide them with proof of mailing. How can I prove I mailed it back? I'm thinking there's also a slight possibility of a lag in crediting my account because of the holiday.