Very Disappointed and shuttered

My sister lost her husband in 2019 and he had left the money which she decided to invest and get monthly interest. The broker took advantage of her level of understanding and her educational background, the broker offered my sister the product and made her sign what she does not understand. Yearly the broker will call and meet my sister at KFC and he will make sure that she's alone. Now my sister wants her monies and the broker told her that the product she took is not possible for her to withdraw the money is a lifetime contract that she can't cancel. The broker explained what my sister wants but on paper is a different things and they made her sign what she does not understand. Please assist as she need all her lumpsum hence she's struggling. The child had to drop out from the college due to non payment and the broker was not answering his phone, they will keep on making excuses that they will call my sister but never fulfill the promise until I used my number to call and arrange a meeting. Even on the meeting the broker kept on explaning to my sister in English and speaking insurance terms that she doesn't understand. My sister told him that she is just signing even though she doesn't understand but under the impression of what they are explaining to her she will get her money. The broker took advantage of the vulnerable and uneducated widow, now the broker told her that he will sue her if she publish the matter. Please assist her to get her money back