I may be wrong but I took that to mean the number

I may be wrong but I took that to mean the number in the box on the upper left hand corner of the Preferred C certificate. It doesn't actually say "Class CS1 Certificate number", it only says "Number"

I also included the CUSIP # on the certificate, number of shares owned at cut off date and the Date on the certificate when it was issued (Mine says: May 12, 2014)

If you don't have the certificate then I would send some sort of screenshot from your broker page showing your shares and when you bought them or some other proof, just to make sure.

If anyone knows something different, let us all know.