The last 4 digits of the master account are listed when you access your account online. Cancel using secure message, and be sure to specify the last 4 digits for both the credit card and the master account. When I got my 2nd business card, I omitted the EIN I used on the first application. Not sure if this was the reason for my success, and am currently contemplating how I can get a 3rd card in the next month or two.