Not doing their investigation and work properly

I had a dispute done on my report and had all the proof that the bank did remove me and send me a letter that I dont owe them money. After 20 days of disputing the matter and updating my report I was told that it can still not be removed. The document that they send to me as proof was not even for me and was for a different person who is under administration. My question is is your staff that imcompetent that you dont read and investigate properly. I will take this matter further with the ombudsman because after numerous occassions me and Nedbank did send requests for it to be removed but still you dont do your work and dont take faults for making mistakes. This is effecting my credit score which you can really take your own damn time to fix.