[enraged_camel]

That's why Scope of Work documents exist: to protect against scope creep.

If a customer demands additional features, you prepare a Change Order and say, "OK, here is how long it will take and how much extra it will cost."

After a while they learn discipline and stop asking for changes half-way (or more) into the project.

Here is another perspective: the vast majority of features I've build as part of Change Orders rarely, if ever, got used. Granted, I make sure all relevant stakeholders are involved in the creation of the initial Scope of Work. That way, there are no late-comers who demand changes/additions.