IMPOSSIBLE TO CHANGE DEBIT ORDER DETAILS - worst experience ever!

I changed banks in Dec17,and had to move my business's debit orders.I called the call center and was advised to put my request to change bank details on a letter head and sign and send to ********** When I did this, the person "Zakariyya Muhammed" rep**** from a "Dealerassist" email informing me that I have to get original 3 months stamped bank statements from my bank(which I dont know as I am new to my new bank and WONT HAVE 3 statements) as well as an approval letter signed by the bank. Now, I dont need permission whatsoever to ADD A NEW DEBIT ORDER TO MY BAN****!!!If I ask you to change or add a debit order and provide you with the bank details, then the institution just do it - because I SIGNED A LETTER ON A LETTERHEAD GIVING PERMISSION TO DO THIS! I told this person that I wont go to the bank to get statements. WHY DO YOU VODACOM NEED MY BANK STATEMENTS TO PROCESS A DEBIT ORDER CHANGE????? You take the old bank details off...and put the new ones on...how difficult can that be? As a result, my January account bounced at the old bank account which was closed start of December - I explicitly told VOdacom that the account will be closed and is empty with NO MONEY and they have to urgently process the new debit order details. After long fights and emails, the abovementioned person advised that the bank details was updated. Only for me to found out today that I am still a "cash payer" and my account wasnt settled via debit order as expected start of Jan and now I have 2 month's outstanding balances. I called the Vodacom customer center AGAIN TODAY and they ADVISED THE EXACT SAME THING - "Please send a formal request to effect your debit order on a LETTER HEAD to ********** now I am back to square one. I will not be paying these outstanding bills, because Vodacom is probably the only company in the world that cant carry out a simple task of changing debit order details to ASSURE THEY GET THEIR MONEY! In that case it is clear that they dont want me to pay my bill!! And even if I have to send bank statements, then all of Vodacoms customer services are not trained sufficiently well to provide one with the correct information, because its evident that both times I called them, I was advised "to ONLY SEND A LETTER ON a letterhead!!!" I will move my account to another service provider that are able to carry out a simple task like this.