How can I add another payment gateway BACS ( bank transfer)

Hi dhuxul14
It's impossible, by default of the Woo-commerce plugin, it provides 1 bank transfer payment gateway for all your bank accounts. In your case, you have to customize by yourself or connect to customized services, where they can help you. Also, you can recommend some plugins as this: https://wordpress.org/plugins/fr-multi-bank-transfer-payment-gateways-for-woocommerce/ but we wont support for it.
Regards