Exposing my confidential information

I asked Nedbank to change the cell number that receives my transaction notifications but they keep saying its changed even though the notifications still go to the old number. Someone else is using that old number and they see all my bank transactions as a result. I have gone to the branch twice and I have called customer services 3 times but they still cant fix it. Im really frustrated now. And to make matters worse, I app**** for an overdraft at the Centurion branch 3 weeks ago and they are still struggling to deliver the service. They keep making excuses for their slow service. Please help.