I see by your profile you are on the other side of the pond so you are likely using different fixtures then we are familiar with. That being said I looked at the Mira web site.
It appears which ever valve you use must have the plumbing in the wall properly roughed in. If you are replacing a Coda (150mm) with the Mode (140mm) you are likely in trouble. The rough-in dimensions are different by 40mm. The Coda has offset connectors but I'm not sure they will offset that far.
If you have links (or model #s) to what you have and what you would like to replace it with it would be much easier to discuss.
"Somewhere a Village is Missing Twelve Idiots!" - Casey Anthony
I never lost a cent on the jobs I didn't get!