More like annoying managment/company

Me and a friend went into 7-Eleven today to get a free slushie. The college here has a coupon book they give out at the beginning of the quarter, and 7-Eleven was in there with multiple coupons for either a free slushie or fountain beverage. My friend got to the register and handed the girl the coupon and she said she they no longer accepted them. Supposedly people made copies of them and that's why they stopped. I'm aggravated because no where in the store (not at the register, slushie/fountain beverage machine, or on the door) did it say they no longer took them in.