Standard Bank offering a better Homeloan Interest Rate than FNB

We app**** for a Homeloan firstly at FNB and then the other Banks, we have all our accounts and Bonds with FNB and being longtime customers, I thought they would offer the best rate. No, no, no, Standard Bank has beat FNB at every turn. We don't have any accounts at Standard Bank but it looks like they want our business more than FNB does, they've offered us a big decrease in the interest rate and FNB refuses to decrease their rate. Is my husband and I not as valuable customers to FNB as thought we were? I am actually shocked, this is our 3rd Bond at FNB and we have a deadline to finalize by Thurs, I really wanted to keep all my accounts at FNB but Standard Bank is looking so much better, my husband now wants to change Banks.