False commitments regarding bond interest rate

Nedbank staff did false commitments to me regarding to give me further discount on my bond interest rate if I open current account with them, now Nedbank is denining to rework on my bond interest rate. Let me brief my story. When I start the bond process, nedbank staff said I can get further better bond interest rate when I open current account with them, I agreed with this and ask her to open my account but she said I can only able to open account once bond is registered. Then I waited for my bond to get registered. Once it's registered, she appointed account staff to assist me with the current account. Now when account is opened, I asked her to rework on interest rate but she said I must move my salary to Nedbank and I did it. Then I asked Jessica again to have a look at my interest rate and she said I must wait for three months to get rework on my interest rate, I agreed and I waited for further three months salary to be credited in my account. Now after three months she is saying that nedbank cannot rework on interest rate as per their policy. I have escalate this issue many times with nedbank but they are not helping me. It seems Nedbank lying to customers in order to increase their count. I request Nedbank to please give me further discount on my bond interest rate as agreed.