octavia II tdi estate rear reversing sensor control module

I have a 2010 octavia II 1.6 TDI estate. The reversing sensors have stopped working. The screen beeps briefly on switch on but no display. I have listened to the individual sensors with ignition on and  reverse gear selected but no sound from any of them.

My rear washer doesn't work either so I assume a leak has damaged the control module.

I found a youtube video on how to replace for an audi but cannot find one for skoda - is it the same? Over rear nearside wheel arch.

I can't find a new control module, lots of used ones on ebay.  is it sensible to try used?

Is the correct reference 1Z0919475 604 056

If I buy a used module can I just swap it over or is there wierd magic to be performed with canbus?

While I am at it, what is likely to be the problem with the rear washer? Is there another control module or is it likely to be a damaged pipe?