A method in a network node comprises: detecting a Quality of Service (QoS) Violated Event in respect of a particular QoS flow of a Protocol Data Unit (PDU) session; and sending a corresponding QoS violated event report to any one or more of: a Session Management Function (SMF) of the network; a Policy Control Function (PCF) of the network; an Application Function (AF) of the network; and a third party service provider.