Shame on you, Nedbank!

I closed my late husband's Amex account with Nedbank, which they confirmed was closed. I inadvertently transferred R10000.00 into the account. Why was this not returned as unpaid? I requested a refund on 12 April. I sent the relevant documents to them. EIGHT emails later I still have not received a refund, only ONE email asking me to resend the documents! This is an egregious failure on Nedbank's part. I am disgusted at the cavalier way I have been ignored and mistreated.