Unacceptable customer service

I would like to lay a complaint with the lack of service I received today when trying to request for a settlement letter from African bank. <br> I made a call at 11:00am today I don't recall the name of the agent that got my call . She asked me a few authentication question and failed one after confirming my ID which gave all the info she was trying to confirm . because my details on their records are very old I have forgotten which address I used in 2008 when I app**** for a loan with them. However I confirmed the flat number and it was just the street number that I couldn't recall at that address . she asked for me to hold on line and didn't explain why I had to hold . at 11:03 came back to the call at 11:08 when returned to the call she asked me the exact shame questions and I then asked her can you not ask me any other questions because these I don't have memory of. she hesitated so much that I asked to speak to her team leader . she made me hold for 15min but still on the line.<br> <br> after she heard me saying i'm going complain she started making sounds to show that she was still there but keeping quite. at that point my airtime ran out .I didn't get the letter but lost my airtime