How do I re-configure a grandfathered account in pro-sites?

This is a pro-site environment. Early last year I changed the names, features, and prices for the various hosting plans I offer. I have a client who created an account prior to those changes and paid for a full year of services. They paid by check so I manually (in December 2012) extended the terms of their account for one year. That client then changed their account to be electronically billed monthly, instead of annually, which took effect in mid December (2013). PayPal shows that the monthly payment was electronically received (in the amount of the original terms), but Pro-Sites says they are an expired account and deactivated the premium plugins. The name of the account type still reads as one of the old account types -- meaning the name hasn't changed to any of the new account types available. I know I can manually extend the account, but don't want the hassle of doing this every month. My current solution is that I manually went in and re-activated the plugins that had been deactivated, but I presume this means they have access to those plugins now regardless of whether they pay or not. Any ideas on why this account is not being "grandfathered" as expected, and/or the steps I can follow for a more reasonable solution?