This happened to me, but I sent CRA what they claimed I owed. I contacted UFILE support and they asked me to send them my return which I did. They sent me an email with the math showing I was right and CRA wrong. I sent CRA the email and received the amount I sent plus interest, but with a note to be sure to count the interest on the next year's return. I have now been "reviewed" four years out of five and proved my return correct every time. The only year I was not reviewed I sent a paper return and plan to do that from now on.
