get yourself some Tilex or make up a strong bleach solution (like 4:1 water
to bleach)

kill all mildew in shower, once and for all (use a respirator, bleach will
age your body faster than anything on earth)

if you still have mildew problems, then you need either:

A. to fix the leak that is keeping you shower wet

or

B. a dehumidifier for this area of your house

showers should not have ongoing mildew problems, it is a symptom of one of
the problems above


PS - tell family members to use the fan when taking a shower to decrease
humidity