Worst standard bank service

Hi my name is Mpho ,last month I requested and negotiated with standard bank to give me a settlement amount on a loan i paid the agreed amount and they sent me a paid up letter .The month end they debited my account and I went to the or Tambo branch and the consultant told me they can't help i I must contact collections department .I got in touch with them and they are requesting a letter and a reason why they have to refund me after I've waited 7 working days only for them to ask for a it.ive been sent pillar to post by different departments.