wipers fail in only two speeds

had a cold snap recently
and afterwards my wipers will only work at top speed or on request

on request the wipers now stay across the windscreen - ie they dont
return to the base of the windscreen

spraying water used to turn the wipers 5 times then stop
now they dont go at all

any ideas?

thought the motor may be gone - but they work in some speeds?
read somewhere might be relays
checked the standard fuse which is ok

garage has diagnosed as some sort of circuit board that sits on top of
the wiper motor - if the wipers are frozen this can get burnt out - i
think it controls the intermittency of wipers - =A320 replacement