I arranged for them to do some work for me and made sure that I was in when they were due to arrive. When they did arrive (late) they claimed that they knocked on the door, but when challenged they changed this to 'rang the doorbell' which as it turns out wasn't working. They then promptly left. So no knock on the door and no phone call. The front window was even open so there was a good chance that there was someone in the house.