How not to get work in a recession

We all know that these are hard times for the building industry and, especially for the small builder, the wet summer weather has not helped either. One told me recently that a job that should have taken five days had stretched over four weeks.
So we should applaud efforts to find work. But they can be counter-productive as in the case of the young man who approached my partner as he was on his way into the house. He was of course 'working in the neighbourhood' and offered first to fix the roof (not our area of responsibility as we are on the ground floor) and then to fix the admittedly dilapidated front path. When my partner said he would think about it and took a card, he thought that was the end of the matter. But no. Fifteen minutes later there was a ring at the front doorbell, and another young man stood there. His colleague had already set to work with a pickaxe. My partner, who has poor eyesight, expressed outrage but wasn't sure what had been done. They said it was an 'honest mistake' and scarpered.
Since when I have been trying to speak to the building company, with no success, and have also been in touch with the police. I would like some compensation. A job that needed doing some time is now urgent as the path is unsafe. And I know who I won't be employing to do it.
We make endless jokes in this country about cowboy builders. It is tragic that so many live up to their reputation.