Can you do any DIY auto work, or know someone who does? The op of this thread had made some progress that you might be able to piggyback on, but unfortunately dropped out before posting a fix (if there was one). If you are not able to follow what he did and continue along that path, you might consider at least trying one thing. In his last post, he had isolated the problem to the OBD 10A fuse. So you could just pull that fuse each time the vehicle is going to be off for an extended period of time. Yes, that's a bit of a PITA, but if it does stop the drain, it would at least save you from buying any more new batteries. And if pulling that fuse really did work 100%, you could even have a toggle switch wired into that fuse. Yep - very low tech, but it would sure beat paying a shop $$$ to find and fix the actual problem. If this drain is being caused by a shorted wire (instead of something being "on"), it could take many hours if digging through wire bundles to track it down.