SOLVED. Spider's Web - girl's mother remarries IT genius, house called Fallingbrook [s]

[Miranda]

I just need the author's name here - I'm pretty sure that title is right but I still can't find the book online. It's an Australian book, I think.
The main character is a teenager named Sara ("Spider") Weber. Her mother remarried an IT whizz and they go to live in his gorgeous and very high-tech house called Fallingbrook (based on that famous house called Fallingwater designed by Frank Lloyd Wright). He gives her a computer which has a personality - this is the sort of technology he invents - it's a cat, and it can also do things like change the heating etc throughout the house on voice prompts. She discovers the internet, and makes a new friend in a nerdy guy from an internet cafe, and his Dad. Her biological father starts trying to stalk her on the internet and the nerdy guy and his Dad help her. In the end he comes to the fancy house but the Cat computer and security system helps her escape from him.

[Diana]

That would be Sharon Stewart.

Spider's Web

[Miranda]

Aha! That is it. Thanks.