Miscalculated my home loan

I'm no pleased the way Nedbank home loan has been treating me. For the past month I have been trying to apply for a home of which I have a pre approval for 750000 but because the consultant are *********** and they miscalculated everything and when I tried to explain they decided to block my application. I'm not happy with the service and people who think that they can do as they please because they have a final say. I'm banking with the bank everything is wlth them but when I need assistance with the most valuable thing for my family someone just block my application purposely and dent my image. I request that my application be revisited my someone else and do the correct calculations.