You can always try for compensation, but it is well within the COC for HAL to perform an equipment change. Aside from a few lacking amenities that you were expecting (never promised) you got to your destination safely and I presume within a reasonable time compared to the original schedule. In this sense, HAL performed as expected and delivered what it sold you.
Look at it this way... the equipment change saved the cancelation of the flight, in which it would have REALLY inconvenienced you. Calling the plane a "flying dump" is a bit of a stretch. Yes, not as modern as the 330s, but hardly a dump.
If there was little or no marketing of the A330 product, then you wouldn't see this post. But
HA markets the aircraft in a big way.
They were actually taking volunteers. If they had announced it was because it's a 767, I would've volunteered and be happy to safely arrive at my destination later.