The milk works better preventatively or at the first sign of infection. It doesn't work very well against advanced case.
Other things to try are baking soda solution:
baking soda solution:
1 tablespoon of baking soda
Ã‚Â½ teaspoon of liquid soap
1 gallon of water
Be sure the soap is soap, not detergent (dishwashing liquid is detergent), which can harm your plants.
Or 3% hydrogen peroxide from drugstore, sprayed straight from the bottle without diluting (test it on a couple leaves first to be sure it doesn't burn your plant).
Alternating different solutions works better than sticking with the same one all the time.