First thing I would do is find the fuses (1 and 24 as listed in the 04 service manual underhood fuse box assembly) and see if they are good. Both going out at the same time seems too coincedental. Then I would find the seat connector and see if the power is reaching it from when you turn on the switch. The service manual has the wiring diagram, so finding the components might be the trickiest. Might be a fuse, module, a connector. You'll not know until you pull out a volt/ohm meter and start troubleshooting. Page 8G-32 in the 04 service manual has the info on both seat heaters inoperative. The heated seat module is part of both seat heater switches, so it might be the source as well. Happy hunting!