I own a shop, and it sure sounds like the heated seats are staying on all the time. If so, then it must be putting a drain on the battery. Are you getting moisture into the car somehow? Check the passenger side floor pan to see if its wet, it may have a leaking heater core, as this will make the windows fog up really bad. Also; feel around inside the trunk to see if you find any moisture around the lower sides of the trunk. I'm thinking the trunk seal may be bad letting water into the trunk. For it to fog up the windows, it must have a leak somewhere or it wouldn't have that kind of moisture inside.
Glad to help out, Good Luck!!!