Section 39C. In any action or claim instituted under section thirty-nine A, it shall be no defense that any common carrier or contract carrier, who has furnished or provided transportation on any such contract, agreed to accept less than the minimum rates and charges prescribed by the department of telecommunications and energy or that such carrier voluntarily made rebates or refunds. In any such action any common carrier or contract carrier shall be entitled to recover the established minimum rates even though the original invoices were presented incorrectly because of the use of threats, intimidation or coercion of any kind.