A system comprising: a charging system configured to charge for sessions established over a packet core network, the charging system comprising: a traffic unit configured to receive traffic reports for a Radio Access Network, RAN, that provides connectivity of mobile devices to the packet core network, and to analyze the traffic reports to detect a congestion condition in an area of the RAN; and a rules controller configured to store service plans for subscribers; the rules controller configured to identify a subscriber located in the area of the RAN in response to detection of the congestion condition in the area of the RAN, to identify a service plan that includes predefined rules for the subscriber, to generate modified rules that deviate from the predefined rules in the service plan of the subscriber to address the congestion condition, and to provide the modified rules to a network entity that performs policy and charging control for a service requested by the subscriber to temporarily change how the service is provided during the congestion condition; wherein the network entity comprises a Policy and Charging Rules Function, PCRF; the charging system is configured to connect to the PCRF over a Diameter Sy interface; the traffic unit is further configured to receive the traffic reports for the RAN from the PCRF; the charging system is further configured to receive a message from the PCRF that includes an Attribute Value Pair, AVP, that defines a cell identifier for the area of the RAN; and the charging system is further configured to receive a message from the PCRF that includes an Attribute Value Pair, AVP, that defines a congestion level for the area of the RAN. a charging system configured to charge for sessions established over a packet core network, the charging system comprising: a traffic unit configured to receive traffic reports for a Radio Access Network, RAN, that provides connectivity of mobile devices to the packet core network, and to analyze the traffic reports to detect a congestion condition in an area of the RAN; and a rules controller configured to store service plans for subscribers; the rules controller configured to identify a subscriber located in the area of the RAN in response to detection of the congestion condition in the area of the RAN, to identify a service plan that includes predefined rules for the subscriber, to generate modified rules that deviate from the predefined rules in the service plan of the subscriber to address the congestion condition, and to provide the modified rules to a network entity that performs policy and charging control for a service requested by the subscriber to temporarily change how the service is provided during the congestion condition; wherein the network entity comprises a Policy and Charging Rules Function, PCRF; a traffic unit configured to receive traffic reports for a Radio Access Network, RAN, that provides connectivity of mobile devices to the packet core network, and to analyze the traffic reports to detect a congestion condition in an area of the RAN; and a rules controller configured to store service plans for subscribers; the charging system is configured to connect to the PCRF over a Diameter Sy interface; the traffic unit is further configured to receive the traffic reports for the RAN from the PCRF; the charging system is further configured to receive a message from the PCRF that includes an Attribute Value Pair, AVP, that defines a cell identifier for the area of the RAN; and the charging system is further configured to receive a message from the PCRF that includes an Attribute Value Pair, AVP, that defines a congestion level for the area of the RAN.