Frustration of the late estate department of Standard Bank

Since my sister passed away in June,I contacted standard bank late estate.Even now the issue has not been resolved.i was calling three times a week but each consultant said they have received the documents until I escalated and communicated with the supervisor but he is not also helping.they r requesting documents that we dont have,like a marriage certificate but we gave them the divorce decree.im disappointed and frustrated as my sister has minor kids and we can't access her money. It was supposed to be 10 working days,now it's more than 3months of not being helped. Standard bank is giving us the run around and I am tired of this