I agree with the other posters. The coupon was given for a specific promotion and by returning the item you no longer qualify. While it may seem silly to you to have to return the coupon, unfortunately in this day and age too many store have serious loss prevention problems. Stores have been forced to have stricter return policies for a reason. I'm not saying that you were stealing; all I am saying is that there are reasons for the policy.

As far as contacting a lawyer, come on! It's a coupon! Paying lawyer fees would certainly cost more than 25 dollars that you would have saved with the coupon!!