Windscreen washer motor on B class 2008

Hi.
I am looking for some advice please. Looks like the windscreen washer pump motor is dead on my B-Class (2008). Volts ok at plug, motor measures open circuit. I therefore need a replacement. Does anyone know how to do this? Is it an easy DIY job or is it impossible i.e. pump welded to tank? I cant see how it attaches down there (is dark when I can look). Are the connections push on or are they crimped etc? Also does anyone know where I can get a replacement pump? I am in Cambridge UK.
Thanks for any help.
Keith.