We require a plugin for WHMCS that will do the following
1)Query For overdue Invoice (60days)
2)Call Overdue Invoice with a payment reminder with prompt:Press one if you wish not to receive this overdue alert.
3)Once the call is placed if they answered or not make a note on the client account about the call.
Things to considered,
Interface in WHMCS to do the following:
1)Setup What to send out
This is bla bla your Invoice Number is Overdue etc etc.
2)Setup what time to make the calls
3)Show what calls have been made and how many time they have gotten the call
4)Show what calls are going to be made, with the functionality to disable or remove that.