hi sams gram-
keep those voice mail messages!
i hear you when you say that child services didn't help last time...but please try again...
your granddaughter obviously trusts you and is communicating she needs help.
you can always call the police and they will do a check of the house for her safety. when she calls next time, you could ask the police to go check on her safety. they will. i've done this before when concerned for a child's safety and the police were on it in a heartbeat.
you might have to play hardball but there is a precious little girl on the line.
getting the police over there will generate a record in their system. start saving all her desperate phone calls. keep a journal of the events she shares with you.
if you let us know where you are located, i would be hapy to do some research into resources locally available to help you.
naive