Ouch, i went through a similar problem, except it wasn't my parents or my front door that caused the problem, but the lift at my place, since if it didn't fit in the lift i would have had to rent a crane and remove the windows to my apartment and lift the tank up 7 Floors...
Either way, best of luck with it... as i'm sure with a bit of tweaking you should be able to get it to fit through your door???