If a retail installment contract or evidence of indebtedness provides for attorney's fees to be awarded to the retail seller, lender or creditor in any action, suit or proceeding against the retail buyer, borrower or debtor involving the sale, loan or extension of credit, such contract or evidence of indebtedness shall also provide that:
I. Reasonable attorney's fees shall be awarded to the buyer, borrower or debtor if he prevails in
(a) Any action, suit or proceeding brought by the retail seller, lender or creditor; or
(b) An action brought by the buyer, borrower or debtor; and
II. If a buyer, borrower or debtor successfully asserts a partial defense or set-off, recoupment or counterclaim to an action brought by the retail seller, lender or creditor, the court may withhold from the retail seller, lender or creditor the entire amount or such portion of the attorney fees as the court considers equitable.