Alert regarding renovation work and inspection commercial law through door-to-door sales

In renovation work by door-to-door sales, consultations such as "I was forced to make a contract and did unnecessary renovation work."
In addition, "Inspection Commercial Law", which visits by saying "I came for inspection" of gas equipment, etc., and contracts products and services by saying "It is dangerous if no construction is performed" or "The replacement time has passed". Consultation has been sent.
Let's not easily respond to businesses soliciting "check for free" etc. Also, do not only give the explanation of the business operator, but refuse any unnecessary contracts.