Becky we have been dealing with the same issues, and sorry to say but at 4.5yo he is no better. Every hairwash is a fight. I have, many times, just dumped the cups of water over his head because he was screaming. Feel terrible about it sometimes but other times I rationalise it to myself that I gave him 40 chances to co-operate and he didn't. I warn him that it is getting done, and that I will do it the hard way if he does not co-operate, and then I go for it. I hate it.
Charlibob gave me a tip that we have had some success with (but not always, because he is who he is!!) and he wears a pair of sunglasses in the bath
I took him to try on loads of pairs and told him what they were for and had him choose a special bath pair. It helps a bit, but the water can still run down between his head and the glasses, but it does help. I think it at least makes him feel like he is being protected from the water. I have asked a dozen times for him to wear his swimming goggles but he won't.
I do give him a dry facecloth/flannel and fold it up and tell him to hold it over his eyes but he does not always hold it tight enough or he drops it and gets angry and has a fit and it all starts again. But he was nearly 3ish before he could even hold it there at all really.
We have one of those pitchers with the soft area for putting against his head, and it pours the water back and makes sure it does not go in his eyes. It works well but you have to pour slowly, I have to still have him tip back a wee bit and make him cooperate. Which is a pain. But it does work well enough.
http://www.amazon.co.uk/Mutong-SC001-Shampoo-Rinse-Cup/dp/B000SQE2KK/ref=sr_1_1?ie=UTF8&qid=1358450924&sr=8-1I have debated trying one of these:
http://www.amazon.co.uk/Clippasafe-CL201-Shampoo-Shield/dp/B000G1TDNI/ref=sr_1_2?ie=UTF8&qid=1358450924&sr=8-2But to me it seems that too many areas are still unaccessable or hard to rinse
What makes it hardest of all is that DS freaks that the water is too cold or too hot. Like, he SCREAMS beyond belief. And between "THAT'S FREEZING" and "YOU'RE BURNING ME!!" is like half a degree
It's all a proper nightmare. Worse in the summer when he comes home from kindergarten with sand in his hair. Nightmare every night.
Hugs