(a) Except as otherwise provided in this Code section, an agreement by a creditor to receive less than the amount of his debt cannot be pleaded as an accord and satisfaction unless it is actually executed by the payment of the money, the giving of additional security, the substitution of another debtor, or some other new consideration.

(b) Acceptance by a creditor of a check, draft, or money order marked "payment in full" or with language of equivalent condition, in an amount less than the total indebtedness, shall not constitute an accord and satisfaction unless:

(1) A bona fide dispute or controversy exists as to the amount due; or

(2) Such payment is made pursuant to an independent agreement between the creditor and debtor that such payment shall satisfy the debt.