The problem being that there are new variants continually sprouting up so scan with both avast followed by MBAM.
Hopefully, they have learnt a valuable lesson, never believe security alerts that don't come from your currently installed security applications. I mean how could it know your system is vulnerable or infected without having either been installed or a scan carried out, the answer is it can't and should be an automatically set your alarm bells ringing, SCAM, SCAM.