Originally Posted by toomanywords
Update now that I've tried this out finally: 1KChinito is, sadly, correct. The type B vouchers, which won't expire for a while, will have to wait for another trip.
Incorrect.
If you have a Type A voucher - which is in effect a "discount" to the price of a ticket - you CAN combine them with a type B - which is "payment" towards a ticket. Most (95 percent) of the ticketing agents don't know this. You should ask for a supervisor or have them call the ticketing help desk to do it.