My Mira 415 Combiforce exposed Shower constantly drips?

My shower constantly drips, I have changed the cartridge and there is no change. I live in an area which suffers from very hard water. I think this may have damaged the main body of the shower and a proper seal between the body and the cartridge is not possible. My shower was installed in 1998, is it possible to replace the old body with the later one which has the changeable strainers. In your opinion do you think this would solve my problem.