I assume that it is this bit on the bumper..... The Ecotec has plain black plastic there, and higher trim models have it painted silver, to distinguish that you have the cheapest trim model. GrrrH! Nots sure if that part is seperate from the bumper, but knowing Ford i bet not and is only sold as one bumper unit.
The way to get round this and likely the cheapest method is to spray it DIY style, ie, plastic primer followed by silver paint. Or go to a local car painter and get it sprayed, I would estimate for front and back to be sprayed would be from £120 to £200. Would likely be cheaper than buying parts, assuming that they are available.
PS....Most cars always do this idea of making the cheaper model slightly different from the upper models, just to make you go for a higher model if you can afford it. its all phycological to make you buy higher trim.
Years ago I had a lower model Honda Aerodeck and the bumpers were just black plastic, and all other models were colour coded, so I got the bumpers painted red by a car paint shop as the rest of the car, to make it look like a higher trim model. So phycology worked on me