R16000 ****** from our credit card

On 25 June 2018 at 16h32, Mrs Florence Nkosi phoned us from ********** 556. She said she is calling from Nedbank regarding greenback points that Nedbank still owed us. She knew all our banking details. She kept my husband busy on the line for 16 min 53 sec. He never got any pop up messages and did not accept anything due to the fact that he was busy talking on the phone with Mrs Nkosi. We received a sms stating that R16000 was taken from our credit card. We gave all this details to Nedbank ***** div. I called this number again on 24 July 2018 at 15h10 and the lady that picked up said she is Mrs Florence Nkosi. I asked her from which company and she told me she is from Absa online (could not hear the rest) How is it possible that the same lady that stole my R16 000 could still be operating from the same phone number after Nedbank had investigated the ***** case? On 24.7.18 Nedbank said they could not give the money back and if we need to stop this lady, we need to go to the police. We are pensioners. How are we suppose to pay back this amount?