As paulmed22 said - ir's under the front passenger seat (under the seat rail at the door side near the front to be precise) - means the seat has to come out to remove it but I managed to get to the plug & remove that, thus saving me the 220mA battery drain that's flattenned the battery twice since I've had it. (about 6 weeks now) The unit was noticably warm when I got to it. I work from home 2 weeks out of 3 so this was starting to become a major issue.
I took a pic of the label on it (3rd pic) and checked with ePER that this was indeed the Blue&Me module before disconnecting it (didn't want to disconnect something like the BCM). I've already used MES to remove it from the Proxy Alignment and stop the mileometer flashing.