Next time you're in there ask for a manager, explain what happened and I'm sure they'll give you a discount. Most managers in restaurants will do something to make things right.
Go back to the restaurant and all to speak with the manager that told you they would send you the coupon. That's bad business on their on part. I always check my order BEFORE I leave. They are known to forget. Good luck!
I also had a similar issue. They took my name, number, and email address, and never heard back.
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