People from Larian do follow the forums, but not necessarily on a regular basis, and they do not post frequently. I'm not sure what the usual response time is for email.
You do need to stop playing (with that character) while waiting for Larian to fix a save. When they get the save file they can load it into some kind of editor where they will be able to check the status and location of any NPCs that are reported to have a problem (or quest status, etc), and make adjustments as required. When they send the edited file back, you should be able to put it back in the save games folder (replacing the original version), start the game, load that save and the NPCs should be restored.
