Wesbank is withholding NaTis certificates on a car that is fully paid

Wesbank has been giving my grandmother the run around.For the past month we have been sending documents and information regarding the NaTis certificate.My grandfather was the owner of this car which he bought in 1995 and never asked this certificate.He has passed away and my grandmother had no need for the car and sold it.This is when she heard about this certificate when the new owner asked for it.Wesbank is still the title holder and we have been requesting it from them.Now that we cleared that up they ask for the documents that's already been sent to them.It has been explained that they are still the owner but again they say if the car has been titled in someone's name they cannot help.WE KEEP TELLING THEM THAT WESBANK IS STILL ON THE TITLE.i don't know if this person cannot read properly