Public utilities; budget plan payment increases. Prohibits a public utility from, for any residential customer who is enrolled in a budget plan or similar billing option, increase the amount of such customer's monthly payment more than once within any 12-month period or without notifying the customer in writing at least 30 days before such increase takes effect. The bill defines "budget plan" as a fixed billing option offered by a public utility to a customer whereby the total service for the succeeding 12-month period is estimated in advance and bills are rendered monthly on the basis of one-twelfth of the 12-month estimate.