Help please

I just had a phone call from a lady she said she was from the mirsoft people she had me to go to netviewer web page and she log in on my computer an she showed me a lot of errors,she said if I   did not get this took care of my computer would crash in a month

so then she let me talk to a tectnecion he told me he would clean  up my computer at a low price of 69.99 he said if I did not it would crash

  he told me that I had to Meany virus protection on it I had told him I had Norton an he seen the malware he said that was what was going on that was causing my problem please help