***** case not getting any feedback or assistance

On 20 February 2015 I received a phone call from the bank informing me of activity on my account which resulted in the account being overdrawn, I informed them that I absolutely did not do the transaction which they described to me and the consultant asked me to contact the ***** department. I then proceeeded to contact them and reported the matter to them where I obtained a reference number, but however since then I have tried contacting tomfollow up and no one can give me feedback on the process. On a daily basis I now receive phone calls informing me that they need feedback as my account is in arrears and this is affecting my credit rating,when talking to this agents they simply ask me what is happening with this matter. Could somebody please assist me to resolve this matter timeously.