We have brought up my grandson for all of his life but his mother has always refused to give us a letter saying he lives with us so she can claim his benefits, she also uses our address as a care address even though i have told them she does not live here. I have tried to apply for the benefits but always been refused as they have phoned her and she says he lives with her. My husband is on ESA and I am disabled, what can we do, she has now given us a letter but she says i can not use it for benefits, she will tell them I wrote it,HELP pls