Are there any limits to the changes a Trustee can make to a Trust?

Family trust originally had three trustees, Father, his lawyer, and his accountant. Trust papers give trustees the authority to amend the trust. Daughter, who was a minor, sole beneficiary. After Fathers death accountants secretary was made third trustee. Trust amended to allow only two trustees when lawyer retired. Amended again to allow single trustee when accountant retired. Secretary, as sole trustee, has amended trust several times over last 30 years, including increasing her annual fee from 1% of value to 3% of value (Value approx. $2 Million) Beneficiary is now living in virtual poverty as trust payment to her has been reduced to only $500/month, plus the trustee sold her family home she had lived in for 60 years and has rented her a studio apartment that the trust pays the rent on. Trustee has told beneficiary that if she complains or seeks legal help she will write her out of trust, as she can use the trusts assets to pay lawyers, while beneficiary is penniless.