A direct vent gas insert we had installed into our prefab fireplace did not take into account that the firebox is raised about 5.5" to provide air intake for the old blower. The custom black cast iron surround provided by the manufacturer looks great above, on the right and one the left. But have this gapping ugly exposed vent below the firebox. We need to cover it with black metal that blends in with the surround. The installer has so far not come up with an acceptable answer. Any suggestions on how we might deal with this (hopefully at a reasonable cost) would be appreciated.