Reapiring the dent are quite cheap and applying back the putty are quite cheap, ~rm30-50... But spraying the paint back is something that will kilss you. 1 door rm200-250. For damage like this, they won't spray the affected area, but the whole door....
I know you are very butthurt on forking out rm750 for this small repairs and looking for members here to support you, but face the fact, this is the price you shall pay.
Or you can dig few more workshop nd ask around, the cheapest you may get is rm700....

Well, you can always ask the workshop to spray partly....

Nope, they are not scammers, is you trying to make it sound that they are scammers.
As said, ask around and see who will do this for you...
Or you spray your self, close case. You only need 3 cans of spray which is rm90 only max.

Case by case and depending on location.... Solid or metallic paint also got price difference...
As long as no photo shown, we won't know the actual problem....