This wording almost ALWAYS gets a reply
AS LONG AS there have been systematic reminders sent beforehand.
As always, start early.
Dear Mr Bloggs,
Please advise if payment for the January invoice 123456 ($6,123.00) and the April invoice 131234 ($3,231.00) has been organised.
If a payment date has already been scheduled, thank you. Please advise when it is to be made.
But, if not, please either settle the balance due or contact me as I have to submit a report to the Board about all overdue accounts this week and, in the absence of any response, they are likely to suggest that we revert to policy.
In advance, thank you.
Why does it work?
Because they probably don’t know what your policy is and what you MIGHT do next. You probably haven’t got a policy anyway!! (Fear of the Unknown strikes again!)