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that is a scam. Nobody is a licensed tech support agent for microsoft. they have dealers and partners that create programs for them. But they do NOT license the people that call up and say they found a problem with your computer.
they probably wont give you back your money voluntarily
what you want to do is
A. call the number on the back of your credit card
tell them that you were defrauded and you "dispute" the charge
the credit card company will put the money back in your account and probably issue you a new card so they cant charge you again.
B. Uninstall any remote access software that they had you put on the computer.
Run malware bytes to make sure they didnt leave any other virus on there that they can use to get back in