We just have sort of "plain vanilla" health insurance. And, the "just because we approved it doesn't mean it will be paid" is always one of those things hanging over your head. Sometimes it's a coding problem. If just the right words aren't use to describe something, it gets counted as something else.
My DD did try a head control. They take a lot of skill to use and since she has good functional use of her hands, we finally settled on a joy stick with a goal post (looks just like a little football goal post). The ball that was on the top of her joystick screws off and the goal post went on in its place. Her biggest problems were that she has variations in tone and when she gets excited, her tone increases, which meant she ran into some walls because her still arm kept pushing the joystick.
The nice thing about the goal post is that you can use it with just gross motor (large muscle) control of your arm. By sitting her hand in the middle space of the goal post, she can drive the wheelchair without using her hand at all, just using the arm muscles. Or she can grab the flat part of the goal post with her fingers and drive it with her hand or even with a limp hand, without grasping. I don't kow if this makes sense, but it's the best I can do.
Her goalpost came as just a bare piece of metal, which I adapted by covering with foam and a little fleece cover. She would have said it was too cold otherwise.
There are lots of things that they can try besides just the joystick. Some of the girls in her dance class have tennis balls in place of the regular joystick balls, some have sticks. etc.