QUICK AT HANDING OVER/ PATHETIC ONCE PAID

I had a Standard Bank loan account, the account was handed over to NDS Credit Managment, I phoned NDS Credit Managment to get the settlement amount, which I paid in full the same day, suddenly I get phone calls from a company called Nimble, saying that Standard Bank handed my account over to them, and I now owe them money as well. After sending everyone the settlement letter and the proof of payment again, and requesting that they send me a letter that this has now been sorted - NOTHING. I keep on emailing them everyday (as what NDS Credit Managment was doing to me) still no feedback at all. I've sent email to [Email Removed] they send a automated response that someone will call me withing 48 hours, for two weeks now - NOTHING. Standard Bank is probably the worst bank today!!! I am now busy getting legal help, I want to take NDS, Nimble and Standard Bank SA to task for harrasment, it is now time for them to pay up!