Quite the contrary
Definition 1 of 1
Pro Tip 1/3Contrast Clarity
Use 'quite the contrary' to make a clear contrast with a previous statement or a common belief. 
You may think I'm unhappy with the results; quite the contrary, I'm thrilled!
Pro Tip 2/3Emphasis
'Quite the contrary' adds strong emphasis, showing that the truth is the absolute opposite of the misconception. 
He seems quiet, but quite the contrary, he's very outspoken in meetings.
Pro Tip 3/3Formal Statement
The phrase is more commonly used in formal or serious contexts, not typically in casual conversation. 
They assumed I was uninformed. Quite the contrary, I had researched extensively.