Open question: Non refundable deposit in Ontario?

I set a non refundable deposit of $20 down on a pair shoes. The receipt was written out with altogether $70 dollar outstanding for a sum total of $90 for the shoes. The secretary explained to me that my shoes for waive on 2-7 days would be present. Some days, after I the secretary mean shoes ordered, call me, in order to explain to me that they estimate me the wrong price had and that the shoes would be $30 extra. On that it was now 6 weeks, since I mean shoes ordered. I too my deposit $20 back-get permitted, or is it really non refundable?