Leaking shower

paddypaws101

I own a first floor flat which I rent out, and have had years of problems with water leaking into downstairs flat.
I think the culprit is the free standing shower unit which is tiled and has a folding door. I have had various repairs carried out to it over the years but the problem always seems to re-occur no matter how many times i get workmen to re-tile, seal etc.

Although it is a feature to have the separate shower and corner bath I am seriously thinking of getting rid of both and replacing with an L or P shaped bath/shower combo. The bathroom is pretty big so no shortage of space.

Any comments and suggestions welcome.
Also....what type/brand of shower would be best in terms of value to buy and install but needing least maintenance. (combi boiler)