Forum:Spell Canceller, Ultimate Offering, Change of Heart

Here's the situation:

Opponent already has Ultimate Offering face up with two monsters on his side. I start my turn.

I use Change of Heart to bring his first monster over. I go to attack his second monster with it and he activates Ultimate Offering to tribute his one remaining monster (the one I was going to attack) to bring out Spell Canceller.

He then says that it cancels my Change of Heart and his monster returns to his side. All during my turn.

Is this correct?