An appliance business is demanding $900 because they claim they arrived at my home and rang me at my workplace and I did not respond. They failed to show the week before and I had trades at my cafe, so I sent someone to wait. They then rang me to say they would come the following week.I specifically stated that I would only be available to let them in between 9 - 11 as I am the cook at my cafe. I did not receive a call . I then received a bill for $135.00. I rang the company and said I was not willing to pay. I also spoke to the owner and told him the same. Where do I stand under the Australian Consumer Law?