In defendant's motion to enforce a prepayment provision under a settlement agreement arising from plaintiffs' suit for breach of fiduciary duty and fraud, seeking to recover an overpayment amount, trial court's grant of the motion and award of attorney's fees and prejudgment interest is reversed where: 1) trial court finding that defendant's payment was made under protest and was involuntary is not supported by substantial evidence; 2) the California Uniform Commercial Code does not apply; and 3) plaintiff is the prevailing party and is entitled to attorney's fees.