Changing shower set up?

[seand]

I bought a house recently as there's a new power shower installed (a Mira EventXS Thermostatic) which is set up to run as a pump shower off the hot water tank, i.e. it will only work when there is hot water in the tank.

I'm wondering if there is any way to change it to operate as a power shower, i.e. so it will automatically heat cold water as required, without having to change the entire shower?

cheers
Sean