My Dad Is 83 Years Old, He Had Quadruple Bypass

My dad is 83 years old, he had quadruple bypass on December 28, 2015. Since that time he hasn't got any better he is on 3 liters of oxygen his blood pressure is good when he is laying down. However, when he sits up it drops to like 93/62 and when he stands up it goes to 60/40.... The hospital where I lived threw him a psych ward 2 weeks after surgery when he was moved to a rehab because he had a bad urinary track infection and because he wouldn't stay in the bed I guess they thought that was an easy way out. There he got no oxygen no rehab nothing! He was there 13 days! Without my consent of course, the hospital had told us he was being moved for intense therapy! Which was a lie! His stats were at one point 97/49 oxygen 79 and they gave him nothing report read: "Resting comfortably"! So now I want to know what is wrong with him and was the hospital part of the reason for his delayed recovery?