The noise you describe has been a "trait" of the FIESTA range fo a number of years.
There is no fix, it seems to be the way the box is bolted to the body which hightens the gear noise through the body and into the car.
Other models ESCORT/FOCUS which use the same gearbox type do not exhibit this noise.
I do know of boxes being replaced and making no change at all, im sure a warranty claim by ANY dealer would be rejected as a result of an attemted repair.
I would confirm the normallity of this noise by asking your dealer to allow you to road test another vehicle of the same specification, im sure it will make somewhere near the same sounds as yours,if so its a case of living with it im afraid!
tony
February 2004