Whoever the 'tech support person' is, this sounds like a scam. There is no need for anyone - repeat anyone - to access your computer to install MS Office. The Zeus Malware is quite old and any moderately competent AV software would have long since dealt with it. In fact, the Zeus is used to "trick victims of technical support scams into giving the scam artists money through pop-up messages that claim the user has a virus, when in reality they might have no viruses at all" (
https://en.wikipedia.org/wiki/Zeus_(malware)). So it's quite possible your 'tech support person' is responsible for this. As for Microsoft vis-à-vis CA7UAL, let's just say Microsoft uses neither CA7UAL nor the Herbert Weiser software/network (whatever that is). I have no idea who Best Guy is - a web search returns nothing I can see of relevance.