I’m really sorry to here you have fallen victim to this – it is becoming increasingly common (in fact I think there was something on the BBC website about it just yesterday).
Large companies are exposed also and have lost £m’s in single transactions (Google ‘fake president fraud’) for full details of how it works but ultimately it is the same fraud just on a larger scale.
The bank will not be too interested I am afraid I don’t think as strictly they have done absolutely nothing wrong. You asked them to pay an account and they obliged. It is not like you made a mistake in the details you entered.
It is purely a police matter.
I know it is too late for you but for anyone else – if you get an email instructing payment to a bank account phone the person you are meant to be checking (using the contact number you have for them and not using any number on the email you have received!) and double check with them.
This kind of thing is only going to get worse so please be on your guard.
EDIT: I insure cyber liability type risks and see this kind of thing professionally.