Jetstar won't return my money!

I booked a flight with Jetstar during the pandemic, but it was canceled in 2021. Instead of a refund, I received a credit voucher. I have since relocated from Australia and can no longer use the vouchers. I requested a refund in September 2023. However, I still haven't received my money, and the vouchers are no longer valid. It seems like Jetstar has essentially withheld my money. I've reached out to their customer care team at least four times since September, and each time, they claim there's an issue with processing the refund. They ask for my bank account details again and tell me to wait 3-5 business days. I'm at a loss about what to do, as I'm making no progress with their customer service team.