California Civil Code
No right of action or defense arising out of a contract for health studio services which the buyer has against the seller, and which would be cut off by assignment, shall be cut off by assignment of the contract to any third party whether or not he acquires the contract in good faith and for value unless the assignee gives notice of the assignment to the buyer as provided in this section and within 30 days of the mailing of notice receives no written notice of the facts giving rise to the claim or defense of the buyer. A notice of assignment shall be in writing addressed to the buyer at the address shown on the contract and shall identify the contract and inform the buyer
that he must, within 30 days of the date of mailing of the notice, notify the assignee in writing of any facts giving rise to a claim or defense which he may have. The notice of assignment shall state the name of the seller and buyer, a description of the services, the contract balance and the number and amount of the installments.