Delta Won't Let Me Use The $55 Change On My Travel Voucher

Delta Airlines gave Treat a $400 voucher when it bumped him from a flight, but it turned out to be something of a trick. When he used $345 of that to buy another flight, Delta’s computer system wouldn’t let him access that final $55.

He writes:

Last summer, Delta bumped me from a flight and gave me a $400 voucher. This past week I was able to use most of the voucher and had $55. left over.

I tried to check my bag with the gal at the ticket counter (she was very nice) and had no problem until I tried to use the remaining funds on the voucher as payment. She checked the system and Delta would not allow it, or there was no provision for it. This is fundamentally wrong for them to extort more money out of the consumer when they still owe me. I should be able to pay them with the money they owe me. I can’t wait for Southwest to come to my city.

Jet-setters, have you ever been unable to use the remainder of a voucher? Any advice for Treat?