Childs SS from disabled father benefits

Here is the sittuation. In 2008 my estranged husband started drawing ss benefits and I was told that she (4 at the time) would also receive benefits. Well, as it turned out, my ex had been double dipping by receiving workmans comp. and ss so my daughters check has never been over $37.00. I was told by ss that the overage that he received is being taken out of her check. She is now 13. I did call ss back in 2014 to inquire when she would receive full benefits. I was told at the time that it would be paid in full in 2017. After going to the ss office today, they say they have no record of said conversation and suggested that I hire a lawyer and sign some sort of waiver?? Please help.