Something that has not been explained is just what is your relationship with the entity that validates your design. Who are they? Without knowing how they fit into the equation you will continue to get differing opinions.
Incidentally most third party conformity assessment bodies will clearly identify the scope of the work they do and my guess is you won't see 'design validation' anywhere.
I can't speak for South Africa but in the EU one of the defences in cases of product liability is that it has been manufactured in accordance with relevant European standards (where they exist).