A group of plaintiffs alleged that a store ran a promotion with an advertisement stating that if customers purchased merchandise for $100 or more, they would get a $50 gift card for that store within 30 days of the purchase. However, the customers who used the promotion received a "$50 off $200" coupon that required them to make a purchase of at least $200 in order to use the $50 credit. Those customers alleged that a contract existed between them and the store because the store's advertisement was an offer they had accepted. Were they correct? Explain your answer and add reference