Replacing a Dual Shower

I have a large (6×3.5) dual shower that needs to be reno’d. The saddle under the glass door is sagging, likely due to a shoddy DIY job by the previous owner. This causes the glass door to scrape. This is the kick in the rear that I needed to renovate this shower, which I’ve never really loved. I’m looking for someone who can replace the greenboard saddle with a marble saddle (recommended by my shower door guy) and waterproof and re-tile the whole shower. Probably will replace the fixtures as well while we’re at it. The handymen I know say this is too big of a job for them, but the GC’s and kitchen/bath co’s say this is too small. Any ideas or recommendations? Many thanks in advance.