(a) When a superior court prescribes an arrangement under Code Section 17-12-4 which involves the assignment of attorneys, it shall prescribe the compensation of the defending attorneys whom it assigns as provided for in this article and approve the expenses necessarily incurred by them in the defense of indigents under this article. The county governing authority shall recommend the limits for attorney fees for the several courts in the county that may be prescribed by the courts for the defense of indigents and such investigation expenses as may be necessary and approved by the court.

(b) Notwithstanding subsection (a) of this Code section, in extraordinary circumstances the trial court may approve the payment of such additional compensation in excess of the limits prescribed in subsection (a) of this Code section as the trial court may determine and find to be necessary to provide for compensation for protracted representation.

(c) The county governing authority shall pay assigned attorneys the amounts prescribed in this Code section from public funds available for the operation of the courts in the county.