Ask them to propose a solution to the issue they have raised. State your view and what you would like from them. Move the other person from a mode of criticizing to problem solving. If she or he continues to criticize, act like a broken record. Then you can remove yourself from the tone of that discussion and put the other person in the position of initiating follow-up.
Nobody wants to be told they are wrong.
Whenever you have reason to believe someone is lying or not making sense, you will not build rapport by pointing it out to them. Allow them to save face and keep asking questions until you lose imagination or control. Even if you have taken the test in the past, take a quick, free refresher course online. When criticized, you are more likely to find resolutions sooner when the other person comes to trust your positive intent. Demonstrate your willingness to find a compromise and ability to be genial even and especially if you don't like the person or the situation.