Hi N.,
My son is 3 yrs old and bathtime and hairwashing was, no problem. In the last maybe 6 mths or so, I have to chase him, to get him in the tub and washing his hair another battle. I cover his eyes to prevent water from getting in them, I have the no tears shampoo, nothing seems to work. He stands up in the tub and says " I want to get out" and then attempts to climb out or grabs my neck to get out. I reasonally purchased a bath mitten in the shape of a duck, because he trys to wash himself up. But I realized it served as another useful tool for hairwashing. When it was bathtime I told him to get his duck and get in the tub, ok no problem. When it was time to wash his hair he says "I want to get out". I told him in a duck voice (sounds silly but whatever works), Duck wants you to stay in the tub and get your hair wash, ok. I did the quack quack noise and he started to laugh, I think his laughter put whatever fears or unwillingness to stay in the tub out of his mind. He then sat down and let me wash his hair. Hopefully, this will continue to work for us and possibly if you would like to try it go out and get that favorite character and happy bath and hairwashing time. GOOD LUCK.
L.