Changing an appointment

Plans change. Here's what happens when you change an appointment, and who finds out.

1. You can change anything about an appointment.
2. Small changes, like the subject or the description, save quietly. Nobody is notified.
3. Changing the date, time, or location of a confirmed job notifies the interpreter by email and on their phone.
4. If the new time clashes with the interpreter's other work, IMP warns you. You can keep them, or release them and offer the job again.
5. One exception. Once a job is on a sent invoice, its billing details are locked, so the invoice and the job never disagree. Fix the invoice first, then the job.
6. Every change is recorded, with who made it and when.

Next, cancelling.