No solution for accounting subscriptions de-registration

I have had the same query with nedbank for 7 months with a resolution. They are unable to re-register me from their own product which debits my acc every month.I have been sent from pilar to post by their complaint managers (Mary Venketasen, Bianca Thompson, Maggie Naicker,Thaythakahle Mbabo). I was sent to their branches and received no help. Now I received SMS from their lawyers threatening to blacklist me. I have been a client for over a decade but the treatment I have received from nedbank is appalling. I have 4 different reference numbers. Where does it all end?