If checks on the bulb, fuse, wiring etc don’t result in a solution then you are left with the dash switch and a module behind the dash. Check the switch. If ok then it could be the module. This is a pcb device that cancels the fog light to off when you come out of dipped headlights/switch the lights off. It was introduced to prevent the rear fog light being left on when not needed.
I had this problem in my Plus 8 . I struggled to get a new module via a dealer or the factory. Plenty for an older Plus 8 but not my 2002 car. I was about to order a unit from CarBuilderSolutions and sort the wiring when a last look under a magnifier revealed a couple of iffy solder joints on the circuit board. I carefully re-soldered them and the fogs worked from then on. I might still have some photos of the module and circuit inside. I took them to send to a deale.
Good luck with your car!
