Change date cause of death in family cost extra $352

I had booked a return flight online for my husband and myself to fly to Brisbane to his his elderly mother who is 80 yrs old, as recently had lost my son due to a motor bike accident. So to get away decided to fly to Brisbane on the 1st March for a visit. In the meantime, an uncle has died and the funeral is on the day we are meant to fly out. I asked Jetstar to change the booking to a later date, that was no problem. Then I was asked to pay on top of what i have paid and extra $352. What the F%@K...they said that they have a compasoniate thing there, and I have to supply a death certificate. Then I may get refunded! I will not be booking with this airline again.