I had been remiss in not taking care of the shower, I use an anti bacterial soap so soap scum builds up, and ventilation was an issue that wasn't my fault. The fan wasn't sufficient. Plus he concrete deck above the laundry bathroom wasn't sealed. So in autumn winter condensation water actually formed on the ceiling. Painters came, striped paint, mould killed it, then id a fresh coat of water proof paint. My lovely mum came and cleaned the shower within an inch of it's life, I can't bend down properly becuase of lymphedema and compression garment. Now after I finish having a shower, I spray cleaning product squeegee the walls, and use a glass cleaner that removes soap scum on the glass, and thoroughly dry the inside with yellow absorbent cloths that work wonders. Plus the builders put in two new high speed fans that sound like jets taking off. Plus an air extractor vent. The ceiling doesn't get damp after a warm shower lasting 15 min, so I take it as a good sign. But I have used mold killer on the cracks and little bits of the shower door etc, just to remove it, along with an old scrubby toothbrush, the shower is looking good now.