2 months and still waiting

Due to sudden illness I was unable to take my return flight home. My sons flew up to be with me while I was hospitalised. One of them was double charged for his return flight home ($459). He was told by airport staff he would be refunded within 3-5 days. That was 2 months ago and he has received nothing.
I was told I could change the date of my return flight (within 15 days) with no costs involved due to Jetstar's compassionate circumstances policy. This was not true either. I had to book and pay for a 2nd flight and then request a refund. Jetstar then refused to refund anything but offered a voucher for future flight - as if I would ever want to fly Jetstar again!
Countless phone calls, emails and complaints on the Jetstar website have had no effect. Perhaps a complaint to the airline customer advocate will help.