I'm running under Plesk 7.5.4 Reloaded under Linux. Very small hosting service with a few clients. Need a simple billing module application that will intigrate with my Plesk Panel. Billing will be automated/manual to read of the expirtion service date listed under each client account, send invoice (with options), allowing a link or payment gateway. Once invoice is paid it will register as such. Need prior notifications before account expires as well as simple server notifications to send to all clients on server downtime, service, and sale changes to emails listed on client panel. A simple trouble ticket interface would be nice but optional.