Being **** to bad service

I have changed my banking details which I called in to African bank and I have changed it with them. I called in to ask If I may have a letter with not even 20 words just stating that I have made arrangements to pay my account every month from that banking account and the amount I will be paying, First I get told they don't give such letters, Then I get told only after 3 months when I called again do they give such letters, then by another consultant I was told my debit did not go off last month that's why they cant give me a letter ? So clearly its laziness to type out a letter as I get different excuses everytime. Oh and the lady at a branch told me Banks don't give such letter, My dear if I should go to my bank now asking for a letter I will get it they will try and assist as best as they can , not bull**** me .