Distraction Burglary is on the increase.
If you have someone knock on your front door and you do not know who they are, refuse entry. Be polite and quick. A simple, no thank you, I am not interested. Then close the door.
Please also be aware that while a person is talking to you at your front door, they could have an accomplice who is trying your back door (which may well be open in this heat).
Often distraction burglary will involve the person (or persons) gaining entry to your home. If they can they will split up, or if alone will ask you to remain in one room while they go into another room.
Common tactics include asking you to run a tap in the bathroom, flush the toilet etc,. while they check the pipes elsewhere in your home.
Unless you have confirmation who these people are i.e. you have booked an engineer to come to your home, or you have proof that they are legitimate (by calling the service they say they are from – do not use a number they have given you, look up the number on the internet), do not let them in, and do not let them keep you by the front door.
If they are legitimate, they will not mind remaining outside (with the door closed) while you check out their credentials. Or they will be prepared to make an appointment and come back at a later time.
If you feel worried, call a neighbour or a friend to come over and be with you.