Section 112C. Any insurer doing business in the commonwealth shall reveal to an injured party making claim against an insured, the amount of the limits of said insured's liability coverage, upon receiving a request in writing for such information from the injured party or his attorney. A reply shall be made within thirty days of receiving such request. Any insurer who fails to comply with the provisions of this section shall be liable to pay to the claimant the sum of five hundred dollars plus reasonable attorneys' fees and expenses incurred in obtaining the coverage information provided for herein.