Citroen C3 - Back washer pump - Depeche

When my wifes C3 is stood without the engine running or key turn on the back washer pump will come on every couple of minutes. I have removed the fuse for the back washer pump and you can hear a relay (maybe) click on and off which I have assumed is the course of the problem. How do a fix this? Or is it a expensive trip to a garage?