Look here:
https://www.showerdoc.com/sirrus-bramham-shower-spares
Specifically:
https://www.showerdoc.com/sirrus-bramham-shower-spares/question/dripping-shower-56747
and
https://www.showerdoc.com/sirrus-bramham-shower-spares/question/shower-still-drips-after-use-102997
There may be other relevant threads but you should be able to go through them for yourself.
Showerdoc may be able to advise on a suitable alternative if yu really want to go that way
sggs
October 2017