Esa pip

Hi I’m on pip and esa I recently got back payment for the server premium esa but the woman on the phone said I’ve only got a set amount back dated to me because someone was claiming carers which I did not know someone was claiming carers allowance for me my grandad was power of attorney over me from when my mum passed away in 2015 I stayed with my grandma for about 3 months and was back in my home I lived with my mum and then I moved to a different area not close to my grandma and she should of stopped being power over me and should of stopped getting carers which I did not know because I wasn’t living with her I had a family nurse that was helping me from 2018 and she was the one that came to my assessment with me when I had another one from esa not my grandma. So shouldn’t I be owed more money of premium esa bevause my grandma was claiming carers for longer than she should of and we hardly talked as I lock myself away I like keeping to myself with my thoughts ect? How do I go about this?