Travel voucher with no option of refund

I had to cancel my interstate flight as the event has been cancelled. I did this online as instructed but was given no option to select refund or travel voucher. I spent 4 hours on the phone waiting to speak to a consultant, but when I finally got through her phone cut out due to poor reception. Then the next morning I see I have been emailed a travel voucher (emailed in the morning) but the total travel voucher is for less than half the amount of the flight. Additionally I live in Perth and you cannot fly anywhere out the state on the amount in the travel voucher. I paid for a flexible flight in case of situations like this but had no idea I was basically giving away money.