How do I prevent Beneficiary Fraud when the trustee won't share any information on the trust asset values?

Trustee has shared a trust document and amendment document. Trust includes real estate, personal property and financial accounts. Trustee has answered other questions, but does not answer specific questions on the value of the estate. How do we prevent self-dealing? The trustee is a beneficiary. There is no will to my knowledge. Is there a certain minimum time limit on this communication.