How to remove shower control (Mira 88)?

[Canuck]

Hi there

I am trying to replace the shower control for Mira 88 to a newer version of same. Can't figure out how to remove the piece in the middle with the dial that controls the temperature. No screws - it might pull off but am afraid to start tugging on it in case this is not how it works and I end up breaking the fittings behind it (which I want to reuse).

Thanks

 

[Hoagy]

http://www.shower-spares.co.uk/mira/mira88_diagram.htm

 

[Canuck]

Hi there

Thanks for the diagram.
But still trying to figure out how to physically remove it.

Thanks though