An agency holding security or collateral which may be liquidated and the proceeds applied on debts due it through the exercise of a power of sale in the security instrument or a nonjudicial foreclosure should do so by such procedures if the debtor fails to pay the debt within a reasonable time after demand, unless the cost of disposing of the collateral will be disproportionate to its value or special circumstances require judicial foreclosure. The agency should provide the debtor with reasonable notice of the sale, an accounting of any surplus proceeds, and any other procedures required by contract or law. Collection from other sources, including liquidation of security or collateral, is not a prerequisite to requiring payment by a surety or insurance concern unless such action is expressly required by statute or contract.