Stop!
You can still re-home your pet responsibly by applying at your local Vet and applying for a Credit Plan like: VetPay, AfterPay, ZipPay, ZipMoney, Humm.
Animal Welfare League provide discounted desexing certificates to those who receive a Centrelink Payment or are under financial hardship. Go to https://www.awlnsw.com.au/branches/ choose a branch closest to you. Either call the number or complete the form online (sometimes there is no online option and you'll need to ring AWL).
If you hold a current valid Government concession, veteran or pension number go to National Desexing Network https://ndn.org.au/