As I am not a lawyer I don’t know the ins and outs. What you risk is a black mark on your Credit Record, a further increase of costs as they CND impose their recovery costs (and declined payment costs). I think you should speak to a legal aid/advice centre that specializes in this area eg https://financialrights.org.au/ (NSW based). This centre is only an example so there may be others around who can/may advise you. I wouldn’t wait to see what happens as the costs if you have to pay may end up being very much bigger than they are now.
My assumption is that you are in NSW from the mention of Chatswood, if in another State there should be similar in it.
