It sounds like you have a faulty flow valve
http://www.showerdoc.com/MIRA-209-70-Mira-Manual-Valve-Assy-209-70
Switch of the power and have a look inside, if the flowvalve is leaking the water may have shorted out the electrical connection andbe keeping the pump running.
Weare having a problem at the moment with our ticketing system it is runningwords together, we have people working on it!!
Ifit is leaking through the shower head then it is likely that the flow controlseal has failed.
http://www.showerdoc.com/MIRA-209-46-Mira-Flow-Control-Seal-Pack-209-46
http://www.showerdoc.com/mira-parent-98-mira-event-(manual)---post-1993
Yes here is the link.
http://www.showerdoc.com/hydr-01102-hydra-sintech-motor-carbon-brushes-(pair)---in-brass-casing-01102
It sounds like you need a new motor and pump unit or you may get away with just fitting a new set of brushes to the motor.
We would always advise changing the complete motor and pump unit however the brushes are much cheaper.
http://www.showerdoc.com/shower-spares/mira/MIRA-209-71-Mira-Manual-Pump-Assembly-209-71
http://www.showerdoc.com/shower-spares/mira/HYDR-01102-Sintech-Motor-Carbon-Brushes-(pair)---In-Brass-Casing-01102