An appeal filed challenging the miscalculation of custody credits was dismissed where appellant failed to first pursue his remedy in the trial court. Appellants letter to the trial court requesting amendment of the abstract did not suffice. Both Penal Code section 1237.1 and People v. Fares (1993) 16 Cal. App. 4th 954 explicitly require a formal motion be filed with the court. The informal procedure relied on by appellate counsel does not meet the needs of an orderly appellate process. The appellate court also noted that although the appeal was dismissed, appellant was free to file a motion in the trial court requesting relief.