Subject to the provisions of N.H. Rev. Stat. § 604-A:6, counsel appointed pursuant to this chapter to represent the defendant, at the conclusion of the representation or any segment thereof, shall be reasonably compensated therefor and shall be reimbursed for expenses reasonably incurred. A separate claim for compensation and reimbursement shall be made to each court before which the counsel represented the defendant. Each claim shall be supported by a written statement specifying the time expended, services rendered and expenses incurred while the case was pending before the court. Each court before which the counsel represented the defendant shall fix the compensation and reimbursement to be paid the counsel for services rendered and expenses incurred while representing the defendant in proceedings before the court; however, no justice shall approve any unreasonable or unnecessary charge.