You completed course work eighteen months ago and since then has worked solely on the thesis. During this period, you have submitted each chapter of the thesis to Professor Z; Z suggested incremental revisions in both methods and write-up which you have carried out. You now believe the original goals that the two of you agreed upon have been completed and you submit the final draft to Z.
Professor Z responds that it is wholly unsatisfactory and asserts that you must not only revise the thesis document, but do additional work on the experimental apparatus and collect substantially more data. You feel that the additions that Professor Z has demanded go unreasonably beyond the original scope of the project and will require another eighteen months to complete.
What can/should you do now?