Change rotten door frame to steel frame

Do you know what will be the cost for changing a rusted/rotten door frame to new  steel frame  and what issue will possible happen?
A contractor may charge you RM 600-700 to change a frame, as they need to dismantle the old one, install back a new one (steel frame from hardware, may cost RM 70-90/unit) fill with concrete, 1 day work.

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Second day plastering the side of frame, if with tiles, need to make it straight. Install back the old door…
Possible issue, the old lock level didn’t match with the new lock level. The new frame is slightly small for the door and the door need to trim.
Hidden cost… Transportation and delivery of steel frame, concrete and skim , dispose of old frame and rubbish. Usually not include painting the edge.
Do you think RM 600-700 to change a frame for 2 days work, 2 worker each day, with all those transportation is expensive?