Letter Threatening Proceedings
I very much regret to inform you that unless your account is fully and finally settled with us before the close of the current month, I shall be forced to entrust the file to my lawyers for necessary action.
Reply to above
Serious irregularities have been noticed in the account submitted by you and unless you are kind enough to submit a proper account, I am afraid I would not be able to pay off just because of your threat of legal action.
I regret I cannot submit to blackmail.