Found some renegade files in a cgi-bin folder... should've thought to look there first.
However, there also seems to be some redirection at play (which I haven't set up), trying to redirect all incoming traffic to the site to the recently uploaded mobi1 template. After I'd removed all template folders you unfortunately get a permission denied message instead of anything else. I've put the host techs on it, but, being the holiday season and all, who knows when this will be sorted out.
I will be setting up a space on another domain for the templates, temporarily, though mobi1 will not be included...
Thanks for the support -- this community is truly the best one around -- and all I can say right now is: blame the asshats.