Looking for suggestions when someone with the early/mid stage of dementia believes scammers who call. Advice?

I have started a new caretaking job for a woman who has Alzheimer’s. She is still quite independent except for: talking in circles - weak/ short term memory; forgets to eat; forgets her medication, etc.
So, multiple times a day scammers call and convince her that she has won millions; however.... they tell her that she has to buy gift cards to provide to them over the phone - before, they give her the money!! (I have reported this scam and so far nothing has stopped the calls) So, as her caretaker; where do I draw the line - when it comes to controlling her choices; ie, who she wants to give her money to? I am there to protect her as well as help support her independence, when appropriate.
The scammers are harassing! They know I am there as her caretaker and inquire as to where I am because they know I am
not falling for their sh**. Others tell my client that I should “take you in town to go get the gift cards...” !
A couple times I am able to convince her that she is being scammed and for awhile she will tell them off the next time they call. However, then she starts listening to them and agreeing to go to town and buy the cards.
Sorry if this isn’t an appropriate topic for this group.