Any reputable company that does duct installations should be able to help out. You'll know if they're reputable if the insist on doing a full room-by-room load analysis before they'll touch the duct system. A good tech can just look at the ducts and often see issues. But that does not give him/her the total picture. So...start with the phone call and the appropriate question, "How do you size ductwork?" If they don't say something to the affect of "By doing a load analysis", or "By Manual 'D'" then keep looking. It'll probably take a bunch of calls before you find the right company. But when you do, please mark their number in your favorites notebook for reference now and forever, as you've found a winner and while costing more, their worth their weight in comfort.
If YOU want change, YOU have to first change.
If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!