Colorbond roof has a sloping side edge meeting a 90cm fascia with two major rust patches on the sheetmetal flashing. Need to replace part of the flashing. It sits under a metal fascia coverplate. Is a 2 storey duplex type of building each owner has 6 metre wide roof from a common apex ridge. Roof has15 degree roof slope. A rusty screw has caused colourbond roof edge to rust. Needs a patch or new sheet. Pls advise cost of both options