The matter of payment services and, especially, the liability regime for unauthorized digital payment transaction(s) is regulated by a multi-level system of rules, comprising European legislative acts (Directive 2015/2366 second Payment Services Directive (PSD2) and the national rules transposing the EU rules), European non-legislative acts (regulatory agencies: Delegated Regulations, Regulatory Technical Standards [RTS], Guidelines, Opinions, Questions and Answers), and the pre-existing general national rules on private relationships. The matter is subject to multiple potential observation points: the tension and coexistence of national rules and supranational regulations; the effect the variety of sources and the fragmentation of governance in the financial market have on the interplay of sources and the theory of interpretation; the regulatory force of soft law.