Old adage is true about "Assume"

You know the old saying about "assume making an bleep out of you and me". Well, for me, that is true relative to getting the dual sided gas fireplace in the living/dining room. I thought, incorrectly, that I was arranging with the heating/cooling contractor to install it. They thought some one was building a brick fireplace and they were only to put in gas logs. There is no brick fireplace and chimney, of course, and I need venting and a 'see thru' firebox to put gas logs into.

I thought I was done making decisions about the fireplace when we decided to create mantels and surrounds in the living and dining rooms matching the existing chestnut one and to face the walls and hearth with marble tile. Sigh. Hopefully, the general contractor will be able to recommend where to purchase the firebox and vent piping and I can get something simple and not too costly.