wcoolnet

But lets say they buy the "extra hour" separate product and then want another hour. They would end up having several "products" in their account even though they don't serve any function other than during the initial purchase.

I'm interested in using WHMCS for WIFI service billing. People purchase a one time package with a certain amount of minutes, then a custom module would create an account for the user with their purchased amount of minutes on our authorization server. I want them to be able to return and buy additional minutes that are then added to their existing account. I don't think I can use the package upgrade option, because lets say they buy a 1hour package and then want to buy an additional hour, that package can't be chosen since they are currently using it. Could I do this with addons or some other feature? Or is it possible to show all packages as upgrade options?