Solicitor

I hired a web designer to redesign my website for a fixed fee. They have completed the project and are now saying I owe them extra “compensation” as it took additional time. They have blocked me from accessing the website and will not handover the passwords to the back end. I would like a lawyer to write a letter informing them they have broken the law by breaking their verbal contract & are obligated to finalise this project. I REQUIRE A LAWYER IN AUSTRALIA & HAVE EXPERIENCE WITH AUSTRALIAN CONSUMER LAW. PLEASE DO NOT RESPOND IF YOU ARE OUTSIDE OF AUSTRALIA.