Projects are complicated. Lots of agreements and changes are constantly made, these should be managed properly.
Document all changes, variations and agreements on your projects. You should put everything in writing.
If you have control of the system at the start of a project, make sure the project (or even at the program level, project office level, or company level) uses …
If, during a project, the client realises a mistake in the scope or specs or one is pointed out to the client and the client authorizes or instructs a change …