The folks over at One-Handed Writers have assembled a set of resources which neatly outline the curious double-standards of pulling down erotica from self-published authors while continuing to sell traditionally-published erotica, torture porn, combat knives and misogynistic books on how to mind-control women (yes, actual mind-control with the intent of receiving actual sex with dubious consent, not fantasy erotica about mind-control).
Take a couple of minutes to look it over. You may well be surprised.
I am grateful to Kindle for providing a means to self publish but they do have one set of rules for Indies and a different set of rules for the publishing houses.
I would love to give away the first book in a series absolutely free, 24/7, 365 days of the year, but only PHs are given that facility.
Best of luck with your issue, persevere etc etc.
You can give the first in a series away free with Amazon. The trick is to list it elsewhere for $0 (ARe, Smashwords, etc), then report it to Amazon as available at a lower price elsewhere.
Amazon will price-match to $0, et voilà!