Thanks to everyone for replying. I was hoping to get a range of opinions and ideas, that of which I did. I appreciate what everyone has said. So here is my take.
The subject company is a small "mom and pop" company. They conduct business via the site I built/host. They also conduct business via outside sales in parallel with the site. What I am going to do is invoice them on the the 15th, they're invoice date with the past due 60, past due 30 and current due amounts along with late fees. However since this invoice will mark the start of the 90 day countdown, I will be requesting payment in full upon reciept. If I hear nothing within 7 days I will send a notice that payment must be received to prevent suspension of service.
I do not care to be cut throat, however after 60 pluse days with 3 months due there tends to be a significant amount of money in which I am expecting. At somepoint the client has to be held accountable. The reason to turn to suspension of services is simply because my calls and my emails neither have been returned.
Again thanks for all the input.
ScoMac