poor customer service

On the 26/08/15 i made a call to mbd regarding my old identity account to make arrangements to settle the whole amount on the same day. I asked the lady I spoke to for the amount and banking details and everything else I would need to settle the account then she told me she will sms me all the details to make my payment, i then did a transfer for the amount i was verbally told and that was on the sms. On the 28/08/15 i received a call from mbd and the guy i spoke to told me i owe R138 for interest and then i asked how do i owe interest when i made an arrangement to pay the amount , he then told me he is going to check the system and then he told me he is sorry for the mistake he has done by calling me because he sees i have settled so i should not worry and he is going to contact the administration department to close off the account and post my settlement letter. On the 31/08/2015 a lady from mbd calls me and tells me i owe interest for R138 and i ask this lady how do i owe an amount when i paid off, she then told me i did not make arrangements with mbd to pay my account??? As the is nothing on the system about the arrangement and i asked her do i work on their system?