Withdrawal woes

If there was a way to rate the service a negative I would. My mother has had a retirement annuity policy with Sanlam for decades. While having the policy, she got divorced and changed her surname. When the time to withdraw the annuity, they are asking for "the full divorce decree". She has provided the divorce decree certificate and new ID copy and that does not suffice. She was a defendant and divorced in 2005 in East London whereas she lives in Gauteng. Even after having explained the situation, they are insisting on the full file which is probably under 20 years of dust. I'm sure there are easier ways to avoid paying out money that belongs to a person who has been diligent and honest with their relationship with Sanlam