Agreed with all of the above. Unless there is something you're not telling us, you followed the rules, you are a OnePass member, you were a OnePass member when you booked the ticket, you booked online, you were told when you booked the ticket (" Note: OnePass members may request a refund within 24 hours when signed in at time of purchase of a revenue ticket. The option to hold your reservation is no longer available."), so dispute the charge with your credit card company.