Has any one had one and had success?

We know where our energy issue is but have no idea how to solve it.

Our hvac unit is brand new and even a slightly larger unit than our square footage needs. Weve have the unit, ductwork, and insulation inspected but the house will NOT stay cool. It has a semi open floor plan. The kitchen livingroom and dining area is all one large room then theres a hallway leading to the bedrooms which always stay cool but the thermostat and the large room will not stay cool period. I live in the south and every day it gets up to 75-77 with the air blasting.

All that said to say we are looking for someone to figure out what on earth the issue is a 300$ power bill to sit in a hot house is very frustrating