Is there any way to set or to zero the temperature on a 5 year old GE profile (double oven) SS23341OP range please?

The oven temperature bears no relationship to what is on the display.

Mine seems completely haywire. When the display reaches (say) 350 degrees, an oven temp gauge seems to be at around 300. Leaving the oven at the 350 setting for a time, the gauge sometimes stabilises at 425, sometimes it goes up to 500 degrees!!

I have already changed the thermostat and it didnt affect the problem at all. What else can I try please?

Or are there only two components to the system, the thermostat and the control panel behind the display? Does that contain all the sensors, chips etc?