JetAus cancelled Sydney–Melbourne and issued a 24-month credit. RESOLVE-AU says Smart Saver fares get no cash refund.
Australian Consumer Law
Consumer guarantees require services be provided with due care. When the airline cancels, you are entitled to a remedy including refund. ACL
ACCC
Denying refunds when the carrier cancelled may be misleading conduct. Lodge complaints at accc.gov.au.
Credit vs refund?
When airline cancels, ACL supports cash refund — credit is not mandatory acceptance.
Fare class matter?
Smart Saver cannot override ACL when airline failed to fly.
Complain where?
ACCC or state fair trading body.