The 10 minutes prior departure cancellation rule is for full refund to the original payment method, i.e. refund to credit card or cash. If you missed the flight without cancellation, you got back SW credit as refund, which has to be used within a year.
For the lowest-price ticket, "Super Web Saver" or whatever, there is no way to get a cash refund for a cancelled flight 24 hours after purchase. You just get the credit for cancelling 10 minutes before departure.
After that, you get nothing. It's in the contract. I think it's only been that way for 2 years or so.
