Inefficent, unco-operative staff

Very disappointed with Nedbank. I got a call from a cashier who asked me to authorise a cheque. I told her that I couldn't do it because I didn't write the cheque and I didn't know that person whose name she mentioned to me. She said she couldn't get hold of anyone else to authorise it, so I must authorise it. I apologised that she couldn't get hold of the others, but she was angry that I didn't want to authorize it. Nedbank is so slow to change signatories and eft system. It is now 7 months that I have been trying but they still didn't correct the information!!!