I’ve not touched the satnav. It just randomly tunes itself to that ‘station’ on the radio.Is it a message appearing when you update the sat nav?
I blame 5GI wonder if it's other devices transmitting that your car is picking up? For example, my TV has a remote that works via RF (not IR!) so perhaps something like that is interfering with it. Radio Ham or CB radio? Or it's a software fault.