So eventually got wipers going again. Problem was that they had a lingering death with several miracle recoveries. When they were working they were fine, no twitching of one blade or anything daft and full communication with the
wiper ecu with the Lexia and no fault diagnosed. However when they stopped working there was no communication and hence no diagnosis. Tried replacing the 'Master' drivers side
motor with a known good one. All was well........for a short time and then they packed up again. Must have been another short lived miracle. Eventually tried a replacement for the passenger side with another known good one and ...voila...all is well again. Moral of the story is don't go with your gut feeling - I was convinced the RHS 'Master' unit was faulty but eventually found it was the LHS 'Slave' than was shot.
BTW new ones would appear to be cheaper than Citroen here -
https://www.allcarpartsfast.co.uk/peuge ... per-motor/ although I haven't used them - I got second hand ones.