If the Authority defaults in the payment of principal or interest on any issue of notes or bonds after the same shall become due, whether at maturity or upon call for redemption, and such default continues for a period of 30 days, or if the Authority fails or refuses to comply with the provisions of this Act, or defaults in any agreement made with the holders of any issue of notes or bonds, the holders of 25% in aggregate principal amount of the notes or bonds of such issue then outstanding may appoint a trustee to represent the holders of such notes or bonds for the purposes set forth in Sections 26 through 28.