I open with "We have an invoice on the Collections Report. I thought I would check with you to see if I can help. Perhaps we are sending the invoice to the wrong address? And do you have our correct mailing address for payment?" Yes. They are our customers. And if you have a good relationship with the AP, you have a better chance of getting paid. That doesn't mean that when they lie to me, or try to stall that I don't get serious. Serious. Not rude. Serious.
If I feel like we are not going to get our money, I have no problem being a little firmer and making myself a pest by calling regularly, daily if I have to. I also get alerts from different attorneys to keep me informed of any companies who have litigation pending or who might be going bankrupt. And then it is just fine with me to get a nc attorney involved. When it comes to bankruptcy, I don't care which end your on, the debtor or the debtee, you need a lawyer with experience in bankruptcy law.
You can still be polite and get your money.
This is a sponsored post however, all the points and views are my own.