Pip payments for time spent at home

Hi all. My daughter was awarded pip enhanced for daily living and mobility in December last year.
my daughter is a 52 wk boarder in a special school due to her severe autism and learning disabilities and the risks to herself and her siblings at home. Under DLA I was able to claim the care element for her when she came home, never had an issue until she was assessed for pip. 
I was told these regular home stays would be paid in arrears once her pip was awarded. I am her appointee.
 I contacted pip in January to give these dates and have contacted them several times giving her monthly home stay dates. She has never received a penny ( except she has a motability car) but has not had any daily care element paid for her time away from the school. The help desk guys at pip can’t tell me why this is not being paid and I have wrote pip a few months ago but had no response and sent an official complaint last month and again no response! The last person I spoke with at pip said someone will call me the same day as this was unacceptable!!! Guess what? No phone call.. where do I go with this now please?
i understand she is in residential school and she had to be ‘looked after’ by the local Authority to gain the funding for her school 5 years ago but she comes home when I have another adult here( she’s 2:1) and she is entitled to receive her care element surely for time spent at home? On her pip award it does say that she won’t receive the daily living care element because she is living in a care home, tbh I understand that as she is there most of the time but why is it different for pip as DLA never hesitated to pay her care every month/6 weeks for time at home? 
Does anyone know?? 
Shes 17 and this money would be so helpful for her as I still buy all her toiletries and clothing and provide spending money each month. 
Who can I contact next please?
TIA