The only thing I have ever had that ate green hair is a sea hare. No snails or crabs ever touched the stuff. BTW, I am not suggesting you get one because they often starve to death in aquariums. Once the hair is gone you need to supplement with algae sheets.
The hair algae does not rely on phosphates alone to survive. You likely have high organic waste content.
Do you use RO water?
What is your phosphate reading?
Do you have a skimmer?
What do you feed and how often?
What light do you have?
Any direct sunlight?
You need to control the algae's food source to control the algae.
By relying on a cleaner crew you are treating the result, not the cause.