Interesting. AC sends me a single pdf entitled "Booking Confirmation" with the Booking Reference # in the title, so easily searchable. It lists all the charges and totals them up into a single total at the bottom, nice and neat. But on my Visa bill it shows as four separate charges, with two different ticket numbers and four different 13 digit reference numbers, but no simple, neat six digit Booking Reference. I guess this is AC's IT department's work again.