Diplomat 1100fda burning out elements?

We've just replaced the fan element of our diplomat 1100fda for the second time and think we've found what's burning them out. When the power first goes on nothing happens and the timer flashes. Once we select manual cooking again nothing happens. When on manual cooking turn the oven temperature up it heats (as it should) but once we switch it back off the element seems to stay heating. Essentially we can't turn the fan oven off without killing the power. When we first turned the switch back to zero the red light stayed lit until we had a fiddle with it! Also, I'm not sure if this helps but when we were first on manual cooking the element seemed to start heating when the dial was turned to the fan picture. I'm not sure if it should be doing that or not.

Is this a problem with the time part of the oven or is there a switch we can change? Is this a big job? Should we cut our losses and get a new one?
Thanks