Be warned-- if you redeem the vouchers online for $100 each (scan in), you will receive a pin code for each one. The issue is there is no way to combine if you book online or by calling into reservations. I was told the best way to handle is fill out the form and send multiple $100 vouchers in and request a pin for the full value. They also said that you don't lose the difference if you purchase a ticket which is less than the pin amount. This is better because the paper vouchers had to be used in $100 increments and you would lose the difference if less.