Phone scam and now e-mail scam

I, too, went through the refund scam but caught on in time, however they keep phoning.  Today I got an e-mail stating that I had authorized a $500+ automatic renewal to their service on my credit card and that I must immediately phone a number to unsubscribe.  When I phoned they attempted to get control of my computer and I refused and hung up the phone.  These guys are relentless.  They often start with a phony internal revenue notification on the phone and they even have a phony bank manager (John Smith, with only the faintest accent).
    They got me the first time by blocking my computer screen with an ad and claiming to be Apple Support who could remove the interfering ad.
    I'm beginning to stereotype any caller with an East Indian or Pakistani accent as a con artist.