When you call back they have a recorded message that claims they we were calling on behalf of "Your Community" from "The Fundraising Centre". With the number of calls they make and the variety of numbers they come from there is no way in hell this is legitimate. It is actual spam. Block them, and all of the following numbers they also call from:

(03) 4251 7523
(03) 4251 7520
(03) 4251 7506
(03) 4251 7501