(a) In all legal service liability actions, any advance payment made by the defendant or his insurer to or for the plaintiff, or any other person, may not be construed as an admission of liability for injuries or damages suffered by the plaintiff or anyone else. Evidence of such advance payment is not admissible until there is a final judgment in favor of the plaintiff, in which event the court shall reduce the judgment to the plaintiff to the extent of advance payment. The advance payment shall inure to the exclusive credit of the defendant or his insurer making the payment. In the event the advance payment exceeds the liability of the defendant or the insurer making it, the court shall order any adjustment necessary to equalize the amount which each defendant is obligated to pay, exclusive of costs.
(b) In no case shall an advance payment in excess of an award be repayable by the person receiving it.