Debit order update..

I have an investment with OM, on the 4nth of July 2019 I changed my bank account and immediately I called *** on the 9nth to update my bank details but I was told couldn't I should call the next day, which I did & I updated my bank details. Month end July OM debited my old savings account with obviously didn't have funds as I moved my salary. So I went to Galleria OM walk in branch, spoke to a consultant and I asked if I could pay cash but they said no I'll get double debited month end August. Month end August came and again OM Debited my empty savings account, I recieved an automated email regarding that missed debit and I rep**** 'PLEASE CALL ME' again I went to Galleria Mall OM and only to find out that my bank details were not updated regardless of replying to e-mails with my new bank details and got a reply that they will me updated *I HAVE PROOF*. At the branch I provided proof of change of bank details and it was "updated" I was told. On the 5th September I got a call from *** a consultant was on the phone with me for 7 minutes she updated my bank details said I'll be double debited on the 28th September as I was behind with two installments and we agreed the second double debit will go through on the 28th of October. The 28th of September came and I was not debited but was only debited one instalment on the cheque account and one on my empty savings account. These two debit were done the 1nd on two different accounts, and again OM tried to debit my savings account on the 3rd *THE CHARGES OM HAS COSTED MAKE ME SO ANGRY* I called *** spoke to a consultant for a good 20 minutes and I asked for an investigation to be done, she assured me that I'll get an email the next day and here I am still waiting. It's so unfortunate that I can't cancel cause I need this money for my son's education. WHAT MUST I DO NOW!!!!!!!!!!!!!!