An insurance company whose parent firm is based in Hewlett is one of three insurers the state is investigating for unacceptable claims practices in the wake of Hurricane Sandy.

Kingstone Insurance Co., and two other East Coast companies had more than the average number of complaints for small companies, according to the New York State Department of Financial Services, which initiated the probe. They are being investigated for failure to send adjusters and process claims in a timely manner, and for the inability of homeowners to contact company representatives.

According to the Department of Financial Services, 66 complaints were registered against Kingstone. The investigation focused on homeowner’s, renter’s, automobile and business interruption insurance coverage. Flood insurance, a federal program, was not part of the investigation.

“These practices and the volume of complaints on outstanding claims are totally unacceptable,” Benjamin M. Lawsky, superintendent of financial services, said in a statement. “New York policy holders have paid their premiums and have every right to expect a timely processing of their claims so that they can rebuild their homes and businesses. We know that the storm produced extraordinary circumstances, but we still expect insurers to live up to the highest standards.”

Kingstone Insurance, which is based in upstate Kingston and part of Hewlett-based Kingstone Companies, allegedly failed to send adjusters, or didn’t send them in a timely manner; sent adjusters who inspected only a portion of residential or commercial property; delayed settlements; and improperly denied wind claims. Kingstone customers also contested their settlement claims, according to the state.

Kingstone did not respond to requests for comment.