Cancellation credit problem

I have an issue with a credit due to Covid19 cancellation s. I have received a credit for $587 but the total amount was $1322!
I have sent of emails and the response that I got was " this is an issue with Jetstar Holiday s and we can't help you" I have tried to fix this online but after spending literally hours waiting, no result! My problem is that I made a payment to Jetstar in good faith I don't care what division I just want my credit. I want someone to contact me that has the authority to solve this.

Australia-Melbourne - Tullamarine
Indonesia-Denpasar (Bali)