Kenwood double oven main oven won't turn on HELP?

I have a Kenwood double Electric oven range CK408/1. For a while now the main fan oven intermittently kept on turning itself off while cooking, also occasionally I couldn't even turn it on at all, no light, no fan, nothing, regardless of whether I was using the grill or other options on the oven etc. sometimes if I pushed the oven knob harder or twiddled with it the light would flicker, then it would start up, but now I can't get it to turn on at all. This very very occasionally happened with the smaller non fan assisted oven too again regardless of which option I was trying to use on it.
However all 5 hob plates have continued to work no problems
I don't believe this is an element problem!!!

Lucy
February 2016