Hi there and welcome Mary
This is a scam, it is not from Microsoft and there are no errors registered with your computer. It is a common scam and they will try to gain access to your computer and your credit card details.
DO NOT give either please. When they call back, tell them you realise this is a scam and tell them not to call again.
If you would like any additional information or assistance, please do not hesitate to let me know. Else if you can take a second to rate my service by clicking one of the stars at the top of the screen then submit, that would be greatly appreciated. Thank you