Complaint Review: National Motors

I went to National motors last Thursday to trade in my 2010 Dodge Nitro to purchase a 2007 H3 Hummer, I dealt with saleman named "Jeff" who at the time when I test drove this vehicle the week before didn't know much about the Hummer any mechanical or electrical issues that I asked to know about.  So I signed all paperwork, brought the H3 Hummer home and decided to try to get my Nitro back.  Went back to Natioal Motors to talk with Matthew Cook fiance manager and to some person who set in this office not sure of his name.  When I purchased the Hummer he was not very customer friendly was in a hurry to get the paperwork done etc.  Well he was very rude upon my return saying "no we are not going to give your vehicle back to you and cancel the bank paperwork,  all sales are final no exceptions".  Then goes and gets me a copy of this contract that I signed.  Well as of Monday a couple things were found to be issues with the Hummer radio volume jumps high and low as well cuts out,  couple speakers on the drive side do not work corretly and lock/unlock power switch does not work on the passenger side.  So I am saying watch this place, the employees and read all fine lines of the paper work.  I am just wondering who will happen when I need to get them to fix the problems with my Hummer since I have a signed as well paid five year warrantly bumper to bumper.