Ooh!! definitely a scam.... and many people have been caught out by handing over their bank details and allowing the caller to take control..
of their computer,and of course end up with a load of Virus and Trojans..
You did the right thing cutting them off..
Do NOT EVER let anyone control your computer, unless you personally know them.
Do NOT EVER listen to their blurb about they are from Microsoft, and DO NOT allow them to convince you they are by asking you to ring their number to prove who they are, as they will just stay silently and wait for you to dial and then someone answers and confirms that it is OK for you to go ahead..
IT IS NOT OK..it is all a scam, preying on good honest people.
They cannot get into to your computer unless you allow them, so dont worry, you are just a random number..