抱怨沒有用得拉。難道你要去告法官嘛？ 再說了，銀行口頭承諾也可以有效啊。

with proper consideration and bargaining, oral agreement could have binding effect as well. 

If you bf can show that he reasonably relied on the bank's oral promise and suffered huge financial loss, he can also sue for estoppel and restitution damages.