I somehow can not help but wonder how long it will take before Jane and John Doe becomes at least a little sceptical. The interest rate on trust is too low on both the net and phone.
When the Microsoft scam first started, I was unaware of it when a neighbor mentioned to me that Microsoft had called her
and was going to call her again in the afternoon as she had to go.
I know how hard it can be to actually get in touch with Microsoft even for companies and so I immediately said that she should not talk to him when he did call her as she most probably was being fooled.
Instead she should tell him that she knew a senior consultant, give him my number and ask that he called me up (Not knowing for sure, I actually got interested).
I never got any phonecall, but talking to my neighbor three days later, I got to hear that she had done as I said and after giving him my number he just hung up 
This time it is the ISP that calls, but take it from me, if you spread malware through mail or otherwise, it is you that will call support because you do not have internet access and you are lucky if you have a mail about it in your inbox if the ISP got it from the upstream provider.
Another thing… A refund is always initiated [B]after[/B] you complaint if at all, come on! 
The bottom two true lines:
If it sounds too good to be true, it usually is.
Common sense, cautiousness and sceptisism - your best tools…