When I start the car and press the clutch everything sounds fine but as soon as I have changed gears and let go of the clutch, the car makes a strange low hoarse-sounding scream. I took the car to the dealership and they have given me a quote of R18600 with R15000 going towards labour. They say the gearbox needs to be overhauled. I just want to be sure whether this is the average cost for a gearbox overhaul or whether I am being taken for a ride.