I cannot stress this enough. Your money talks! When we invest in something we are sending a message that we value that product. Same goes with our banking, our insurance, our superannuation and our utilities.
These decisions can't be taken lightly and proper financial advice needs to be sought. But I cannot promote this website enough!
To help you out, some friends of mine that volunteer for ARRCC have been running workshops on this for a while now. You should check them out. https://www.arrcc.org.au/go_fossil_free_individual
To find out more utilities, you might also want to check this list from greenpeace. https://www.greenelectricityguide.org.au/
And when you are making any other purchase decision, you might like to check out this website and app. https://www.ethical.org.au/3.4.2/