I am replacing a wall unit AC for my parents that was running on a 220 line, 18,000 BTU standard three prong plug. I have purchased a new unit that is 25,200 BTU • 220 Volt 20 Amp Dedicated Circuit (Perpendicular Plug). I wasn ot aware of the plug diffrence. Do I need to return this or can I somehow alter their outlet receptical to accept this "Perpendicular Plug". I have been looking all over and there is no information anywhere! I was trying to do something nice and I am so confused and frustrated! Please help!!