Why does my bank wants me to send them a W-8BEN if I live in the US?

I have a bank account in Bank of America and they are adamant that I should send file a W-8BEN, even if I live in the US and I am taxable in the US. I already told them about that but they keep insisting that I should (falsely) state that I’m not a US person for tax purposes. They keep sending letters and telling me over over the phone or in person to do that. I wonder if I’m the wrong one here.