I did not. I have basically given up on the DotNetPanels built in billling system. I could not even get it to generate the recurring invoices. No one at DotNetPanel support even replied back. I dont know folks are actually using DotNetPanel for billing. (since it doesnt work)
So, I am in the process of building a VB.NET application that will do the following.
1. Generate recurring invoices
2. Attempt to authorize the credit card using Authorize.net
3. Send notifications to the customer
4. And a few other things.