If the controller is labelled as a XS-2015 and the customer has 15amp power supply to the spa they are able to purchase the SN-XSRH3000(3kw Heater), should be run with either a circulation pump or two speed pump.
Also check the dip switch is set to load shed.
Spanet XS Series 2kw replacement element XS-RH2000. This heater can be fitted to a XS-2000 and XS-3000.
Comes with leads and sensors only no unions included, please note the new heaters are blue in colour (sv mini) however correct plugs are fitted to suit xs series