Section 28. The exemption provided by subsection (a) of section two shall not apply to the provisions of sections twenty-five, twenty-six and twenty-seven, except that a card issuer and a business or other organization which provides credit cards issued by the same card issuer to ten or more of its employees may by contract agree as to liability of the business or other organization with respect to unauthorized use of such credit cards without regard to the provisions of section twenty-six, but in no case may such business or other organization or card issuer impose liability upon any employee with respect to unauthorized use of such a credit card except in accordance with and subject to the limitations of said section twenty-six.