Hi QP, The tracker is the usual culprit. As they hit 5 years old, the internal battery in the unit gives up and they then scavenge from the main battery, voila!
There have been other issues such as seats and hifi draining, but 9 times out of 10 its the tracker. Most people just unplug it. I dont know how much the battery will cost but you can be sure it will be pricey from the main dealer. Get them to remove the unit, the source your own battery if you still have the Navtrak enabled, oh and be prepared for a call from them if you do.
Great to have you onboard, look forward to seeing some pics.