I just cashed in some vouchers for a ticket. Booked through 1K reservations and held until I went to the SAN ticket counter.

I presented the agent with my PNR along with 4 $50 Type B VDB vouchers and 2 $65 Type B refare vouchers. Was told that they weren't combinable. I thought he was balking since one of the $65 vouchers was in my wife's name, but he said that the bump vouchers weren't combinable with the refare vouchers. Of course I got a 1-time exception and only had to pay the remaining $10.

I don't know if this was correct, but this time it worked out in my favor.