Beware of this scammer

Have seen others here mention his name, [Edited: "Name"]. My husband received a call from him last Friday, telling us he worked in Xfinity's Security Dept in Philadelphia. He proceeded to tell us a"bad actor" had accessed our router and tried to purchase Bitcoin in our name, and added he would send out a technician to add a SONICWALL device, costing $500.00 His explanation was that any time there is detected fraud like this it is required that the FTC be contacted and this device installed. Also said Comcast would monitor our account for the next 72 hours. He told us to pay via pre paid card. We called back the number and he answered, but this phone could have been located anywhere. I looked at the emails this guy sent: the grammar was off and there were misspellings. Another email that confirmed the appt included "dead" links that were made to look like official Comcast/Xfinity links. We called Comcast and they had no record of the appointment and could not confirm this person's identity.  We were also unable to log into our gateway since Friday's phone call.  

We decided this was a scam after being on the phone with us for almost 2 hours. Since then we have made changes to our gateway router and will officially report this to Comcast.