Reich Bathroom Mixer Tap ...pump stopped working?

Hi all,
In our 06 Elddis Super Sirocco the bathroom sink mixer tap decided to stop working yesterday for no apparent reason, until I found out that my other half had accidentally turned on the tap while I was pulling water in to fill the tank :-)
I've just checked the fuse box all ok there, the shower and kitchen tap are both working fine.
I'm assuming that perhaps the switch could have been damaged or disabled in some way.
Can anyone give any pointers on where the switch is located, if I might be able to do a part replacement such as a mystery in-line fuse or if I might need to replace the whole tap?
Thank you all in advance for any help :-)