Refusal to release Natis document

My son left for overseas employment on Saturday the 2nd Feb. He settled his ABSA Vehicle Finance last year. ABSA Finance did not release the original Natis document at that stage and now are insisting he email them. I, on his behalf submitted a letter he signed together with a certified copy of his ID, as I sent the email they now refuse to act on the letter. This is pathetic service and they should have released the Natis document when the account was settled.