Nedbank debit order date change.

Nedbank Fail. I made contact with Nedbank to change the debit order date for my Homeloan, little did I now that it does not matter how much notification time is given to do the date change, I still need to make 2 full bond payments (one on the old date and the other on new). As I’m pleading my case to the nonchalant consultant on the line I am forced to take my “arrear payment” and divided it over the longest possible time period, in this case, 6 months. Can someone please explain to me in simple layman terms how does something like this even start to make sense? And of course, my natural feeling with this situation is to move to any other service provider, as I feel hard done about this. Is there anyone else out there that had an experience like this?