Neff Oven ignoring timer?

I have a Neff U1421N1GB/07 electric oven and have a problem with the timer. The timer display works as does the simple countdown timer function. However, if I try and use the delay start or timed start and finish functions the oven ignores the settings and is on all the time. For example, if I set the timer to turn the oven off after 30 mins there is a click as the timer reaches zero but the oven stays on.

I am planning to take the oven out to replace the fan motor which is showing its age and sometimes needs to be encouraged to start. If I know what component controls the oven on/off from the timer I could replace that at the same time.

Any advice (or better still a part number!) would be appreciated.

Thanks