Early debit with no agreement from me!!!

I called Nedbank call centre x2 today , 1st time I spoke to Verushka, and 2nd time I spoke to Mashudu. With Verushka I advised her that I did not agree to have Nedbank debit my account earlier in December. She advised me that they sent me an sms in November 17th. On trying to explain that I did not receive any sms the call cut. I had to call back as I did not receive the courtesy of receiving a call back. The 2nd time I held on the line and eventually landed up at Mashudu, who firstly interrupted me while I was doing the security check, then when I told her what the problem was, she then needed to me to do the security check. PATHETIC! I DID NOT RECEIVE YOUR SMS!! If I did, I would have called sooner, as I do not GET PAID on the 15th and there is no funds in my account. She proceeded to tell me that I will be LIABLE FOR AN UNPAID DEBIT. IF I RECEIVED YOUR SMS I WOULD HAVE CALLED EARLIER. My account is paid diligently every month! The only way I knew that Nedbank attempted to deduct, as my own bank sent me an sms. When I wanted to speak to a manager I was put on hold for 9 minutes (as my phone records convos) then I GOT CUT OFF AGAIN! Your service is extremely poor & pathetic