It sounds like it's an issue with Future Flight Credit, not TravelBank? Regardless, I had this happened to me recently, and, from the agent's perspective, there a number of people involved to get it resolved, so get ready to be on hold for an extended period of time while they resolve the issue (~1 hour). Basically, call reservations, have your PNR and/or ticket number of the cancelled reservation handy, and explain that you never receive the Future Flight Credit refunded (assuming not TravelBank).