Restaurant.com Internet rip-off took the gift card amount but didn't give me the credit Internet

I received a Restaurant.com $25.00 gift card for purchasing $50.00 or more from a company called BookRFun. I signed my card up to a restaurant called Margaritas in Perryton, Tx. My husband, grandson and I went to eat at this particular restaurant and ate supper there. When it came time to check out, the cashier redeemed the card but it didn't change anything on the bill. I called to check my balance and it was zer. Evidently when the cashier hit redeem it took my $25.00 credit off of the card but didn't send it to the restaurant. I had to pay the whole bill plus lost my $25.00 credit from Restaurant.com. I spoke to the manager and she said the card is a scam. She has asked several times to be removed from there website as a participating restaurant. She stated that she never receives the money from the card. The compay keeps their money!! This is a SCAM and a RIP-OFF.