Can a full blood transfusion be used to change your blood type?

A woman I work with said that her cousin was given a full blood transfusion to change him from A- to A+ (or the other way around) because his mother was the opposite type, and at birth they had the rhesus negative problem (I don't know all the details). She said that this happened before the shots were available (sometime in the late 50's, early 60's). Is it possible to change a person's blood type entirely? How would their organs function? I don't know enough about our pyhsiology to know if this would work. Help me out?