Door skin and entire door are two different animals.

Replacing the skin keeps the door frame and you re-weld a skin on the outside. It is a lot of work. A lot of shops don't re-skin doors because the labor cost is just as much as a new door - it's that much work.

It is cheaper and more efficient to find a parted out X5 and grab a door from that, otherwise take it to a body shop and they can fill it and repaint it.