No Voucher, No Refund and CSO acted like they couldnt hear me and hung up

This has got to be the worse airlines ever. My flight was in March and till now i am waiting for a refund. I had spoken to them 2 times this week and both time they promise a callback and I dont get a call back. i know when they put me on hold to review my short case file, they are just taking a break and not doing anything. The last call was the worse. After promising to put me thru to their manager, they came back and acted as tho they couldnt hear me and hung up. Jetstar CSOs are the worse lying scums.

International
Singapore-Singapore
Australia-Melbourne - Tullamarine