To end your frustration, have an attorney review your paperwork and write a letter to the company demanding payment. If you and your brother are named beneficiaries you should be able to accomplish this fairly quickly and inexpensively.
I agree that if you are beneficiaries (like an insurance policy) then you should not need probate at least as to this item but obviously you are not getting anywhere on your own. The POA is not valid after death so that does not matter.
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There is an estate. You need to talk to a probate attorney. If the value of the estate is less than $150,000 then you can file an affidavit for probate of a small estate. There is NO durable power of attorney that is valid. Once a person dies, then a durable power of attorney is invalid and it cannot substitute for a will. You must probate their estate.