I'm afraid that adding anything to FAQ will work with this problem of yours.
the easiest way to handle this is,
Add Gig extras for Extra Revisions
At the beginning of the Order, let your client know about your revision policy. be very polite and explain it to them. be careful Not To sound like you are running after money for extra revisions!
if a customer asks for revisions after order completion anyway, well.... you don't have any option if it gets to this stage. Rather than risking a negative review, see what you can do about it, do it and then explain...
But always be very clear about,
WHAT YOU DELIVER
and WHAT YOU DO NOT DELIVER
At the beginning of the Order! that way I guess you'll be able to avoid this in the future!
wish you all the best and take care! 😀
-Harry