Back payments

I just received my first disability ck this past month. In my award letter it states that my back-due benefits were 13,944.00 and that they withheld 25% ( 3,486) for my attorney fees. I received my back pay in 2 checks, one for $2138, and one for $8026. There is a $294.00 difference. I never applied for or received SSI and have brought this to their attention every time I speak to them, but they never get around to anwering my question, as to the $294.00 I was shorted. Anyone know how I can resove this? Thanks