Front wipers on a 2010 Fabia are only working in certain positions. Intermittent and Fast work ok, but slow and wipe once don’t work. Screenwash and rear wiper works ok. I’ve changed the control stalk, wiper motor and checked all the fuses but the fault is still apparent. 
Anyone have any experience of this fault and any suggestions? 
Many thanks. 

It sounds strange that intermittent will work, along with fast whilst normal will not. I don't actually think you have a wipe once function, unless you have what people call "Teardrop" Function programmed, where after wash-wipe, you get one extra wipe to clear up any remaining drip.

 

I seem to remember a fault years ago on my Fabia, where the wipers had a fault and it turned out to be its control unit or module. The workshop dismantled, cleaned up all the terminals as they had become corroded enough to prevent current from flowing, and re-assembled everything. I was advised that if they became faulty again, I might need to replace the unit but from then to now, its remained fault free.

MRGF - thanks for the information. Do you remember where this control unit is located?