Hellsbrink, uploads and downloads when remotely-controlling a machine in the office do not occur on your local network.
They do if you up/download to the machine you are working on, not only the one you are remotely connected to.
For example. She accesses her work PC and downloads a document/whatever to work on at home. That is downloading to her "local network".
I don't know the full scenario regarding what osmosis was up to to crunch his bandwidth limit so quickly (he also has to bear in mind that the data limit generally includes uploaded data too, not just how much stuff is downloaded) but it is possible that there was a sharp increase in data use due to the missus' "remote" work not being as "remote" as it seems.