I think the issue here is BOI refusing to action requests to close credit card accounts.
I too have recently written to BOI requesting that they close my credit card account. I paid off my balance, paid the credit card levy, and asked for a statement that I'd paid the levy so that I could get credit for it on my new credit card.
They cleared my balance, they applied and cleared the credit card levy, but left the account still open. The blatantly ignored my request to close the credit card account.