Nedbank deceased home loan

My mom had a home loan with Nedbank, the home loan is fully paid off and has a cession with a life policy from old mutual. I have been trying to get a letter to indicate that Nedbank has no interest in the home loan anymore as it was paid off in 2016. I have been calling nedbank and going to their offices(who say they can’t help me, this is only done via phone call). When I call they refer me to a deceased email address which is never responded to. If I was looking for a home loan they would have assisted me already but because it is something that will not benefit them they conveniently are not a Ai le. I have a letter from the executors but Nedbank still refuses to assist me.