Subject to Subchapter C, a preferred provider contract must provide for payment to a physician or health care provider for health care services and benefits provided to an insured under the contract and to which the insured is entitled under the terms of the contract not later than:
(1) the 45th day after the date on which a claim for payment is received with the documentation reasonably necessary to process the claim; or
(2) if applicable, within the number of calendar days specified by written agreement between the physician or health care provider and the insurer.