TTTG - sounds great that you're enjoying the service with us. It's important to us that all customers enjoy their hosting with us.
Yes, anything unused in your account will be credited towards your dedicated server purchase. For example, if you paid us $100 and you used our service for 2 months (and its $10/mo) It would be a credit of $80 ($100 what you paid us to start the account - $20 for the used service).
Hope that clears it up.
