Unauthorised Debiting of my Account/********** Upgrade

On 1 December 2017 MTN took about R1000 off my bank account. I phoned and was told I upgraded my old cell phone number. I did not. I submitted the necessary documentation for a ***** investigation. It has been 2 months and MTN have given me no feedback on what has transpired. The debit order of R1000 is still being deducted off my account by MTN. I have spoken to two managers who have both undertaken to revert to me and did not. I have sent numerous emails to Customer Care only to be told the matter is still being investigated. I was initially told the investigation would take 21 business days. I am incredibly livid by MTN's lack of interest. I am of the opinion that this is an internal ***** that has occurred! The next debit order goes off tonight and MTN have the audacity to call me today to offer me an upgrade. Absolutely ridiculous!