I can understand some of your frustrations. The truth is there is not much you can do.
If your mother is of good mental health and has the mental capacity to make decisions, she is allowed to make "poor" decisions.
The only way you would be able to make decisions on her behalf is if her mental capacity deterioted (and a judge, with opinions from medical doctors, agreed with you) and you were mentioned as the power of attorney for medical decisions.
I hope this helps
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