wiper blade system

[ccl]

The wiper blades when on intermittent setting sometimes goes slow other times runs faster but still intermittent, however there is no way shown on how to choose the slow intermittent or slightly faster intermittent. Does anyone know how to do this as there is not dial, knob or lever to do so? Or do we just allow the wiper blades to do as they wish?

[Vauxhall Owners Club]

Sounds like the rain sensor (if fitted) may be covered in muck, try cleaning at the top centre of the windscreen and see it that works