wanna know my right

I bought a used pre/pro from a dealer based on the fact that the unit has been factory upgraded for dts, I was told. After taking it home, I learned that the dts was not upgraded. I brought it back to the dealer, and they verified my claim that the unit does not have dts upgrade. They offered me a full refund. The dealer was at least honest.

However, I wonder if I have some right to have them dts-upgrade the unit. I spent one day listening to that unit and finally liked it. I went through a very hard decision to buy it (the unit was not cheap to my standard). I want the unit with upgrade as the original deal. Not the refund with my day/mood wasted. Am I asking too much ?

Ken