I've gotten plenty of certificates from restaurants who gave me "a bad delivery experience", without my asking. I didn't even consider the experience "bad". It was something like the driver had a flat tire, called me and said he was going to be late and then said he would have the food remade. I said don't worry about it, bring the food cold (pizza) and I would just heat it up. I didn't even think about it anymore. But I still got a free coupon.