Cable TV provider Spectrum is suing the state over a Maine law that requires it to return a portion of a customer’s monthly bill when service is discontinued.

The refund was mandated under the state law sponsored by Rep. Seth Berry, D-Bowdoinham, who said hundreds of Spectrum cable customers complained of a change in billing practices that left them on the hook for charges. Gov. Janet Mills signed the bill into law in March.

Spectrum Northeast and its parent company, Charter Communications, contend its regional billing system is set up differently and that the new law would cause irreparable harm.

Spectrum said it allows customers who terminate their service to keep their cable for the month instead of offering a prorated refund.

The new law is due to go into effect June 16.