Unless there has been a fairly recent change, and I'm not current on all things SW, you can definitely extend ticketless travel funds. There is a $50 fee, charged per ticket, not per confirmation number. Certainly worth paying it if you have $700 in credits though. Note: if you have multiple small credits, look into combining them to book one more expensive ticket, then cancel that - it won't extend the expiration date on the credits, but could save you some money on the per ticket extension charges.