Deceased estate

My grandfather passed away 3 years ago, and Absa Trust, Santie Herbst was put in charge of handling the deceased estate. My mother and uncle's portion has been paid out a while ago, but my aunt's portion, has not been paid out. My aunt lives in USA. Absa requested documentation from my aunt, which she sent to them a long time ago. Each time she does get hold of someone, something else is apparently needed, but everything has already been sent. (And they acknowledge receipt thereof) She has made numerous calls and sent countless emails, but has had no valid response.