We bought a restaurant.com which was $10 for $20 worth of purchases. After looking over the menu and deciding what to buy, the cashier took our order and hit "validate" on our voucher before knowing what to do with it. She called the manager over who began to try and say that he never put his coffee shop on restaurant.com and that they did it "without permission" and he would not accept the groupon. After being upset because we had already purchased the groupon and the cashier had validated it, he said he would only honor a 20% off our order. He tried arguing with us about what we paid for the original voucher and we ended up just walking out.
Here's a tip: even if you took your business off restaurant.com "2 weeks ago", you still need to honor the customers that bought one. We will NEVER be back. I've been here once before and the coffee was nothing to rave about and no cheaper than Starbucks. And combined with awful customer service like that, they won't make it very far.