Checkride Re-Take, Oh My!
Go for it. The only way the FAA knows of bad egg examiners is when the applicants speak up.
From the Designated Examiner's Handbook, any applicant may request a checkride re-take from the FAA for any reason. The FAA is obligated to give you a re-take. It will be a full checkride, Oral and Flight. There will not be any credit given for any successfully completed tasks from the DPE. If you pass, the failure is wiped from your record. If you fail, well, the FAA confirmed the failure by the DPE. I do not know if that counts as two failures or not.
It is possible to re-take an FAA checkride, even a "709" ride, under the "that guy was being mean to me" clause. Use different wordings of course, but know that both you and the inspector giving you the ride are thinking the same thing.
Expect the first question out of the Inspector's mouth when you ask for a re-take is, "Does this person have a history of mental problems?" Assume that the Inspector will think you are nuking futs and prepare accordingly.
Expect the meanest SOB in the FSDO to be assigned to give you the re-ride. If you are 11 degrees off on heading during a maneuver and the standards are 10 degrees, you will fail.
Believe me, you will know a h*ck of a lot more by appealing the failure than just walking away.
A good way to approach this is to call up your local Safety Program Manager and ask for advice. They love giving advice. Tell this person the whole story and ask what you should do. They're Safety, unless there is an imminent threat to life and limb, they can not do anything enforcement- or certificate-wise. But they can tell you which Inspector to discuss your situation with and what to have with you when that occurs.
Sleep on it. Talk with your instructor in the morning. And call the FAA when you are done with the CFI. You don't want to wait for months then have to re-train for the checkride. You may even be able to take the re-ride with a "I want to get the checkride over with, then I will consider a complaint against the examiner."
I know of someone that wrote a textbook, almost, while asking for a checkride re-take and got it granted. I know of another fellow that called up his Fed, said his checkride bust was bullhockey and got the re-ride the next day. Both persons passed their re-ride easily.
Good luck!
Jedi Nein