What can I do if someone doesn’t follow a will?

My grandfather passed away a few months ago. He had given me a copy of the trust and will, as I was named second trustee should the first not perform. The trust is not in probate as everything was in there and it is just a matter of liquidating assets and distributing them. My aunt is the trustee and I feel she is doing some shady things: 1. My mother was explicitly left out of the will and my mother told me that my Aunt is giving her 12%. 2. My aunt told me the estate total is $170,000. My sister and I were both supposed to get 15%, but we only got checks for $18,000. What can I do about her not distributing the trust as stated in my grandfather’s will?