Over time, different legal models of third party-financed sales contracts have evolved. The “Credit Construct”, in particular, presents certain problematic aspects that cause controversy among jurisdiction and jurisprudence. § 13 of the Consumer Credit Act, originating from the implementation of Art 3 lit n and Art 15 of the Directive 2008/48/EC (Consumer Credit Directive), only contributes little to a better understanding of this complex subject matter, since this provision lays down the conditions for the ground of defence, but not for a rescission under the Law of Unjust Enrichment in the event of exercising this legal remedy. In this respect the legislative materials refer to the General Law of Contract and Unjust Enrichment, which, however, does not always lead to proper results regarding third-party contracts. Within the scope of this thesis the problems of third-party financed sales contracts will be discussed based on a specific hypothetical case. The facts of this case were prepared in a highly practice-oriented manner. The results can be generalised and applied to a multitude of real cases.