On Tuesday, during Amazon’s Prime Day, festivities, the online retailer’s credit card partner Visa joined in the fun with a promotion where customers who made a $150 purchase using their Amazon-branded Visa card would receive a $30 discount. That’s an appealing bargain, and plenty of customers prepared to take advantage of it. What they didn’t do was read the fine print, or take it seriously, and a lot of customers missed out. [More]