We have a number of payment systems currently integrated with KashFlow, BACS unfortunately will not be one of them. Have you tried using something like Go Cardless?
With the implantation of our Bank Feeds last year, you should have a much easier time with updating your bank account. Whilst this will not automate the entire process for you, it will allow you to keep track of payments made from bank accounts etc.
KashFlow Product Team
I don't think admin has read and understood the request properly as GoCardless is inbound payments and not outbound.