Insurance problems

I received an email from children's mercy saying our insurance will not pay for the wheelchair because of pre existing conditions.I called the insurance company and the lady was RUDE not nice at all and made me mad.I asked her why it is pre existing because the benefits handbook states a child adopted or born with sp needs pre existing conditions do not apply.
She informed me that there is a pre existing clause(harrumph bull crap) and its because he did not have insurance prior.This is the most stupid thing i have ever heard.I told her Um he was an orphan from another country their was no insurance.Monday i am calling someone else that i think can help me with this matter.I am not happy.
My biggest thing is..they pay for his specialist visits and they pay for his hearing aids and his therapy.Why not the wheelchair.They said if it was not for this Claus it would be paid for.I will fight this.Jax needs that chair.He needs good back posture when we are out.He is getting to heavy to carry and we really need this chair.