Shower too strong, waste not quick enough

[secretemp]

Hi, first time here - i'm not a plumber but have a question please (i did try and search in case this has come up before but i can't make the search facility work!).
My sister and her husband have just had a shower fitted and tiled (walls and floor) - but the water doesn't drain quick enough for the powerful shower - so rather than having the tray taken out and waste pipes rearranged, is the next step to reduce the pump in some way or get a less powerful pump?
Thanks

 

[ajs heating]

you can get a less powerful pump, but that a exspensive route to take.
why not try not turning the shower up so high when your using it.
but long term it should of been checked before fully install as if the pipes have a bad flow on them they are more incline to get blocked in the future.