FNB Bond on 2nd property

I have been banking for FNB for years. I wanted to purchase a 2nd property for rental income and investment. All other banks would approve the bond but FNB would not approve the amount. They said the value of the property is lower than what the developers are selling it to me for. Why would all the other banks approve and not the Bank I bank with. Useless FNB, and no phone call from the manager or anyone who can explain.