In cases where the low normally provides that a contract must be in writing, consumers have the right to nonetheless prove the existence of an unwritten contract. This can be accomplished by presenting supporting documents or witnesses showing that the business operator has issued a notice, advertisement, or warranty or has otherwise acted in a manner indicating to the consumer that the business operator agreed to give goods or services or perform in any way in exchange for the consumer' s promise to enter into the contract. this right to prove a valid, unwritten contract includes situations in which the business operator agreed to grant rights and benefits to the consumer in addition to those included in the initial contract.