In Ohio, unjust enrichment occurs when a person "has and retains money or benefits which in justice and equity belong to another." citing Johnson v. Microsoft Corp., 106 Ohio St.3d 278, 286, 2005 Ohio 4985, 834 N.E.2d 791. Restitution is available as a remedy for unjust enrichment when the following factors are established: (1) a benefit is conferred by a plaintiff on a defendant; (2) the defendant knows about the benefit; (3) the defendant retains the benefit under circumstances where it is unjust to do so without payment. Hambleton v. R.G. Barry Corp. (1984), 12 Ohio St. 3d 179, 183, 12 Ohio B. 246, 465 N.E.2d 1298. Unjust enrichment operates in the absence of an express contract or a contract implied in fact to prevent a party from retaining money or benefits that in justice and equity belong to another. F & L Ctr. Co. v. H. Goodman, Inc., Cuyahoga App. No. 83503, 2004 Ohio 5856, at P15, fn. 2, citing University Hosps. of Cleveland, Inc. v. Lynch, 96 Ohio St.3d 118, 130, 2002 Ohio 3748, 772 N.E.2d 105. Unjust enrichment cannot exist where there is a valid and enforceable written contract. Id.