I was having a problem with my Hotmail account so Googled "Microsoft technical support.". First listing seemed very much like Microsoft company so I went to the site. It turned out to be Guru Aid, which skillfully made it seem that they were contracted to Microsoft to provide free advice and support to users. I used the 0800 number provided and the representative told me he would solve my problem. I asked if they were contracted to Microsoft and he said they were. I naively accepted his word and allowed him remote access to my MacBook Air. After a little while of him commenting on how slowly my machine was running (it had not been!) and how it needed a good clean-up (it is scanned every week!) I became suspicious. He then he would have to pass me on to a more senior colleague, and that this would involve a small charge I immediately told him I would seek Apple's advice on the problem and closed my laptop down. Two days later the inevitable happened....my machine went crazy and a message appeared saying I should call Apple Support immediately for help on the 0800 number provided. A quick check confirmed it was not Apple so I rang the correct number for Apple and explained my issue. The representative was brilliant and very reassuring. She said she would be able to trace any malware or adware that may have been planted, and would be able to remove it at no cost (Apple actually mean it!). By screen-sharing she guided me through everything I needed to do, detecting several alien plants, and how to remove them. Thank goodness, no use had been made of them, they were just lying in wait to be remotely activated. This is the first problem I have ever encountered in 25 years of owning and using computers (my own fault I admit) and I have absolutely no doubt that it occurred as a result of my contact with Guru Aid. I find many of their excellent reviews on this site to be incredible and would suggest people thinking of using them to refer to some of the American sites carrying reviews. They are horrendous!