I called back number (02) 9219 2100 rang 2 times then goes to busy tone.

Keeps ringing. Missed the call each time but number suggests it Mission Australia's head office

received call but missed it. Internet search shows a number for Mission Australia

Had a missed phone call from this number and let it ring out they did not leave a message I tried to call them back and it just rings with a dead engaged tone there is no ability to get through to them how come I can ring one way and you can’t return the call?!

I called back number (02) 9219 2100 rang 3 times then goes to busy tone.