If a party denies existence of the arbitration agreement, he may petition a court to stay commenced or threatened arbitration proceedings. A petition to stay arbitration shall be filed with the court where a petition to order arbitration has been filed. If a petition for order to arbitrate has not been filed, the petition to stay arbitration may be filed in any court subject to venue provisions of Title 6 of this article. If the court determines that existence of the arbitration agreement is in substantial and bona fide dispute, it shall try this issue promptly and order a stay if it finds for the petitioner. If the court finds for the adverse party, it shall order the parties to proceed with arbitration.