I am in a ruff stop, my 3 kids want to live with me but Dad has primary custody?

I have 3 kids from my first marriage. They live with Dad at his parents (for the last 6 yrs). The kids all share one room, no air conditioner (they have to sleep on the floor in grandparents room because, its so hot. that is the only room with air) or heat and are emotionally abused. I have called children and families and they have done nothing. Their ages are 11 boy,10 & 8 girls. Any advice on what I should do next.... I really don't have money to reopen our case. Are there any child neglect laws they maybe breaking. I live in a home where they all have there own rooms.