What if the waitress doesn't honor your coupon?

I post some restaurant coupons from time to time. Just to make it more convenient to my friends. Some of my friends come back and tell me that the restaurant didn't take the coupon. Some individual operators like making up their own rules. Right! What if the waitress doesn't honor the coupon? That does happen! Here is some real examples:

• Swiss Chalet at Woodbine and Denison refused to take the coupon Swiss Chalet Canada - Free Appetizer & Dessert with entree. They insisted on seeing my SPC card, although I made it clear that the requirement is not printed on the coupon.
• Quiznos in Commerce Valley accepted the i-Coke 2 for 1 coupon but gave me two sample size subs. Here is a new Quiznos Sub Canada Coupon: Free Cookie with Sandwich Purchase coupon.

This is Toronto. There are lots of restaurants and tons of choices. Sometimes they need their customers to remind them who their real boss is.

Quiznos requires the customers to present the coupon before order. Here is what I do:

1. Order the Sub as usual.
2. Grab a seat and wait.
3. When the Sub is ready, grab a cookie and present the coupon to the cashier.
4. If the cashier rejects the coupon (whatever the reason is), just ask them to keep the Sub and walk away slowly.
5. The owner asked me not to go and accepted the coupon.

As for the Swiss Chalet, here is what I do:

1. Order everything as usual.
2. Present the coupon for the free appetizer and dessert.
3. If the waitress rejects the coupon, request to see the manager.
4. If still reject, go away and eat next doors. What about Kelsey's who accept coupons without any question?
5. The manager asked me not to go and gave me something even better than what the coupon offers.