Double Debit Order

It's been over a year having the same problem with nedbank homeloans, they've been double debiting my account, having to call the bank every time to be told it's done and won't happen again, going to the branches for help and not getting any, my livelihood being disorganized just like that each and every month. Having my other debit orders bouncing because of this incompetence. The calls i make, the traveling to the branches for the same thing over and over, it's really tiring. May i please have someone who knows what they are doing fix this mess for me...