how do i fix the shower?

In older cisterns if water is dripping out of the overflow pipe, try adjusting the cistern float level, but it is likely the ball valve washer will need replacement. You may need a professional to do this. You could also try bending the float arm.
http://www.wdbathrooms.co.uk/acatalog/Baths__Whirpool_Baths_.html

dimi
July 2008