A maintenace contract are used to provide maintenance on your website. Not to create a new website. A maintenance contract is used for after the launch of your website, and most designers/developers state a specific time that you have to completely review your website for errors. The time frame is generally a week.

If you think you can just send tons of changes to your developer and expect them to not charge you for the work then you are mistaken. I only make minor changes within that week period. If you want to completely change the content you are going to be charged for my time.

Tip1: Save your changes and send them all at once. It will cost you more money to send items piece meal.
Tip 2: If you have a signed maintenance contract you are somewhat protected from price increases. All designers change their rates from time to time.