Anticipating change and the likely need for future renegotiation can enable the parties to plan for it, and that preparation can provide a more cooperative environment for making changes. At the heart of a successful relationship is the initial agreement that considers as much of the future as possible. If you've done it well, it has an enormous amount of flexibility in it. That's the key.
Businesses just change a lot today.
Therefore you need to have flexibility in the agreement to address these changes. The issue that arises in the purchase of additional services is when the customer and vendor disagree about the type of services included in the initial agreement. As an example, Ciecimirski cites what could happen in an agreement for outsourcing services. It could be hidden because the work is being done or budgeted outside of the process area or because the employees weren't absolutely clear about what they were doing. So when that task comes up, the vendor says it's not their job, and the customer says it is.