If this has happened to you

A stranger asks for remote access: what to do

1. Hang up. You do not owe a stranger a reason, and you can always ring back on a number you looked up yourself.
2. Do not install anything they suggest, and do not let anyone connect to your computer.
3. Never read out a code, a password or a card number. A real company does not ask for one to prove who you are.
4. If they claim to be from a company you use, hang up and ring that company on the number on its own website or on your paperwork, not the number they gave you.
5. Tell someone. A second person in the room is the cheapest security there is.

If you have already given access

1. Disconnect the computer from the internet: unplug the network cable, or switch off wi-fi.
2. Get the remote software removed. If you are not sure how, ask someone you trust to do it, or take the machine to a repairer you know.
3. From a different device, change the passwords for your email and your bank, and turn on two-step verification where it is offered.
4. Ring your bank and tell them what happened, especially if any card or account detail was on the screen. Ask them to watch the account.
5. Report it (the listings below take reports from the public) and keep a note of what was said, and when.

Habits that make the calls pointless

• Let an unexpected call go to voicemail. Real organisations leave a message and a number you can check.
• Start from the company's own website, typed in or bookmarked, rather than from a link, an advert or a number on a screen.
• Treat urgency as a warning, not a reason. Nothing genuine collapses in ten minutes.
• Never pay in gift cards, and never send money to an account given to you over the phone.
• Keep the computer's own security software updated and let it do its job. You do not need to buy anything from a caller.