TD4,wiper problem

Hi guys ,back again with a little problem and seeking advice from you.Today after driving with no problem i slowed down at a roundabout and an avalanche of snow descended from the roof and came to rest at the bottom of the windscreen thus preventing the wipers which were on intemittent wipe from returning to the bottom of the screen.I switched them off,stopped and removed the offending snow.
Since then the wipers work on speed 1&2 but do not park,on intermittent wipe they stop in twice across the screen during each cycle and using one wipe stop as soon as the switch is released.
Can anyone tell me if this may be a relay problem,motor parking problem or something else.
Both wipers still cover their original sweep and have not been moved by the snow.Thanks,Graham
Ps.have to say the car has been great in the snow today,would be even better if i could see where im going properly!

Three possibilities I can think of.
1. Two fuses in passenger compartment fuse box are used for the wipers. Fuse 3 (20 amp) and Fuse 8 (15 amp). Check them both.
2.The wiper motor has the Park switch built in it driven by gears. By stallng the wipers whilst still having power to them , may of broken or mis-aligned them. Only changing the motor or taking it apart (if that is possible)and checking it may solve your problem.
3. Wipers are controlled by the central control unit (CCU) it has relays and semiconductor switches in it. You may have fried one of these.