Can a common law breach of contract between two parties contracting at arm's length constitute an unfair business practice?

involved in a class action) can constitute an unfair business practice' " under the Unfair Competition Law. (Arce v. Kaiser Foundation Health Plan, Inc. (2010) 181 Cal.App.4th 471, 489-490.) But the parties have directed us to no authority, and we have found none, that declares a common law breach of contract between two parties contracting at arm's length constitutes an "unfair" business act or practice under Business and Professions Code section 17200.