Nedbank Bedfordview

My Mother passed away on 29 May and we were instructed by her Bedfordview to write to Nedbank Deceased. Other than a reference number we have heard nothing since. I phoned her branch and was told to resubmit her papars to Deceased Accounts which we did. Nothing. I have written to complaints three times only to be told they will look into the matter. Nothing. Her account is not yet frozen and we cannot sell her property because Nedbank are the Executors to the estate. Are we able to apply to have Nedbank removed as clearly they are not interested in the matter.