Did Lowe's sell me the wrong door?

I just had Lowe's remove an old double entry door system that was in poor condition. It was replaced with a single door and two sidelights. The new door's threshold is 2" higher than the floor and is now a trip hazzard. Did they install a door made for new construction rather than a replacement door? Is there a difference? Please help me understand what happened so I can at least know what I am talking about when I face them later today. Thank you very much. Dave