Cannon 10545g mk2 ignitor problems?

Hi I currently have a Cannon Chester 10545g mk2 cooker,the faults I have are that if the main oven supervision device (part no. c00240999) is connected electrically it instantly blows the plug fuse when plugged in. With this disconnected the top oven/grill and rings will all ignite correctly if the control pannel isn't in manual mode, i.e. flashing A displayed not cookpot. If you put the cooker into manual then the ignitor will start sparking immediatly and not stop unless you put into auto then finish auto so it goes back to displaying flashing A. one day it worked fine next day whilst cooking it took out the fuse and failled to work unless as described.
Suspect might have a couple of faults.
Any ideas.
Cheers.