Best method of repairing plastic door frame
I personally do not think a PVC cement will give satisfactory results. I would probably:

1) find a thin gauge aluminum channel that fits over the broken frame, deep enough to cover the gouge, spray paint it to match, and silicone it down over the length of the frame. Or,

2) use automotive body filler, plane and sand to blend, than spray prime and paint the entire lower frame (perhaps this is similar to the "bond and fill" product you found, if so give it a try!)