I've provided design and drawings to a property developer(his company actually, as he's registered a Pty Ltd company for this project). He's failed to pay my invoices, abandoned to pursue the planning permit, but took the drawings to the real estate agent for advertising and is trying to sell the site as it is. Can I sue him for copyright infringement and how can I calculate the account of profits? I have to put some figure in my claim and to pay the court fees depending on this figure.