windscreen wipers not working correctly?

hi i bought a citreon c3 sx 06 plate 1.4l and found the front wipers were not working i looked around and found the plug at wiper motor was not connected so i plugged it in the motor worked on slow speed but i cant make it go faster and the control arm does not affect speed even after i turn off ignition the wipers keep going in slow speed can u possibly tell me what u think is wrong or what best course of action would be thanks any help advice is greatly appreciated