[onlycafe]

first thing to do is name the restaurant and see if anyone else has gift cards too!
then everybody shows up at the same time, wait a minute, i have a restaurant. never mind.

seriously, if they are a reputable place they should certainly make good on the amount one way or another. offer to use them with fifty percent in cash until the amount is cleared.
at least that way they will not be subject to slagging on the net.