。
I'm not satisfied with what you did.
Literal
I [topic-は] you [possessive-の] did [nominalizer-こと] [to-に] satisfied-not.
満足する (まんぞく, 'to be satisfied') takes に for the thing one is satisfied with. ~していない = not in the state of being satisfied. やったこと ('what you did') nominalizes the action with こと.