How can I get the heater to warm up the foot area?

Hello, that seems quite abnormal that the dealership suggests it cannot be fixed? I would expect that the ventilation system would project heat through floor vents - that's how it works. If there is no heat in the floor vents, then it would seem to be a mode door issue preventing the air from flowing where it is intended to flow. Check again with your dealership; compare to a like vehicle for example. I think you'll learn more once comparing it against another vehicle. Good luck.