Should I repair or replace my Redring Superflow 3000 ?

I have a Redring Superflow 3000 shower, which now seems to be suffering from a worn pump. It has had some heavy use over the festive period with house guests. It now makes a funny noise and then runs colder, and the pressure drops. It doesn't happen all the time, but frequently enough to be annoying.

Should I fit a new pump, if that is what the problem actually is, or should I just replace the whole unit with a newer model. If so what model/make would be the most appropriate as a direct replacement?

Thank you