At this time we still have not heard from you in regards to invoice #12345 for $___ which was due on ___nor have we gotten a response to numerous phone calls, emails, or the letters sent on ___,___, or ___.
Because we have failed in our attempt to work this out with you directly, I regret to inform you that we have reported this issue and turned this invoice over to a collection agency who will be in contact with you in regard to the payment of this invoice.