No Vouchers offered

I have just been on the phone with Jetstar for the 4th time regarding a return flight from Adelaide to Sydney and back in late February 2021. The 2 shows we were going to attend have unfortunately had to cancel the shows due to Covid restrictions.
Every time I have called they tell me that because the flights are still going they will NOT issue me with a voucher so can go to the rescheduled even. They tell me to wait a few weeks and then call again as the options may have changed.
Today I was told that Vouchers probably will not be offered but I could change my flights for $55.00 each way! I explained that I had already paid that to change 2 flights to the ones I have now.
Basically if I can't afford to pay another 2 flight changes or they won't give me a voucher they told me I would loose all the money I have paid!
I don't understand why they won't just give me the voucher as I will still be flying with them when the event is rescheduled to next year!!!!!!!!!!!!!!!!!