1 Acts 2003, 78th Leg., R.S., ch. 562, § 46, eff. Sept. 1, 2003, provides that the change in law made by that Act to Section 712.028, Health and Safety Code, applies only to a contract for the purchase of a plot in a perpetual care cemetery entered into, or the exchange of a plot in a perpetual care cemetery made, on or after September 1, 2003.