On our new house the HVAC contractor missed a portion of our LL hallway (instead installed in dead space & closet under stairs that wasn't supposed to have in-floor). This hallway connects a bedroom to the rest of the house and a bathroom so rather than the warmer floor it was supposed to be in cold MN winter, anyone in this bedroom now gets a cold floor anytime they go to the bathroom or shower or to/from their bedroom for any reason.

Secondary issue is the wasted heat in the dead space and a storage closet that can be over 90°f.

Fixing this is probably not reasonable and would require ripping out wood flooring, concrete, wall trim, likely some sheetrock, etc.

What is reasonable compensation for a miss like this?