Thanks. Nobody seems to want to talk to me yet though!! Lol!

Hi Everyone. I am new here but am hoping you can offer me some advice. I have a daughter who is now 16 years of age. She was born in England. After separating with my wife at the time I continued to support my daughter directly, but then she (who was born in Australia) decided to return to Australia and take my daughter, and a daughter from a previous relationship who I also brought up, with her. As you can imagine I was not happy at the time. Her deciding to move to Australia made it extremely difficult for me to have regular hands-on and financial control/involvement with my daughter which she agreed but and chose to move to Australia anyway not caring about me or my involvement. I have maintained contact with my daughter throughout though. In 2009 I moved to Canada to live with family and am now awaiting my approval for Permanent Residency. I have a signed letter from my daughter's mother dated in 2009 confirming that she has no outstanding issues with regard to Child Support for my daughter, as this was required for my application. A few days ago, and totally out of the blue, I received CSA papers from the Australian CSA demanding over $13,000 (over $4,000 of which are penalties) in payments for my daughter?? The mother's financial situation and train of thought has obviously changed and she has decided to claim support dating back years!? My questions, that hopefully you can help me with, are: 1. Can the Australian CSA legally chase me for payments when I have not lived or resided in that country. My daughter was born and predominantly raised in England? I am English. 2. How can I be charged penalties for monies/payments that I have never been aware of from a country that I have not resided in? The mother has always had my contact information as I have stayed connected. She obviously hasn't informed them of this as they are claiming that they have been trying to contact me for years??? 3. I have a signed letter from the mother from 2009 (which she has obviously forgotten about) stating that there are no outstanding Child Support issues to date. This also proves that she was in contact with me at that point. I have been sent residency forms and a breakdown of fees owed from the Australian CSA to my Canadian address but am hesitant to respond without finding out how I stand first. If you can provide any advice and what I should do next, or how I should respond, that would be fantastic! Best wishes, Dunny