Money paid incorrectly

My husband paid a big amount mistakenly to an ABSA account on the 19th of Jan 2022. Since then we have been struggeling with them to get back our money. The person whos account it is have passed away in 2010. They were not even aware of the person that passed away. The account has been running for 12 years. There is also no executor for the person that passed away. Our bank has also tried to recall the money. But since we said to ABSA that the person passed away they put the account in late estate. Now we are being sent pillar to post to get the money back. The money does not belong to the person whos account it is, the person passed away, so they will not be able to contact the person whos account it is. We want our money back. The Late estate department can also see when the account has been put under late estate. Late estate advised us that we must just go back to the branch and ask them to remove the hold where it was implemented. We did that and still we are having trouble getting back the money.