The manager at a local restaurant,  Nara Express in Lenoir , recently yelled at my wife for asking to combine two of their promotional punch cards - something I've never had any business that uses such a promotion as much as bat an eye about.

Punch card's are a Customer Loyalty Promotion. They're designed to increase the visits of established customers. Ineffective at bringing in new customers but effective in getting current customers to return more often.

Customers regularly can't find or don't have the card with them and start new ones at business that use such a promotion. Merging punch cards is a standard procedure because of this. The idea is to create loyal customers. Hassling them over merging punch cards is NOT the way to create a loyal customer. It is in fact, a good way to create the exact opposite.

Badly played Nara Express of Lenoir. Yelling at your customer/accusing them of doing something fraudulent will lose customers rather than create loyalty. I know we'll no longer be customers.