I called in order to get information regarding the...

I called in order to get information regarding the return side of the duct work system in my house. There is a single register on the second floor down a hallway from master bed and bathroom ,the room seems to stay much warmer than other areas of the house. My understanding is that the bed room door would need a very large door undercut or a transfer grill or a dedicated return , or some type of low resistance path returning air in order to balance the system. I spoke to a sales type person with limited information, and informed me that they do not do any work with the existing duct work and were unable to provide any information at any price. They were of course able to quote me new system install. Which is unbelievable to to put a brand new air handler in a house and not have the ability or the willingness to know , in any way how the rest of the system is functioning. An assessment and balancing of the existing duct system even a part of the installation of a new unit, is not something this air conditioning company is interested in or capable of doing.