(a) Before an amendment of a credit transaction may take effect it must be:
(1) confirmed in writing;
(2) signed by the consumer; and
(3) returned to the creditor.
(b) The writing must state:
(1) the terms of the amendment; and
(2) the new due dates and amounts of the installments.
(c) The creditor shall:
(1) deliver a copy of the writing to the consumer; or
(2) mail a copy of the writing to the consumer's address shown on the credit document.