Amazon.com Amazon Marketplace Amazon.com does not resolve undocumented credit card charges. Seattle, Internet

Unknown charge appeared on personal credit card bill from Amazon Marketplace. I had no record of the charge in my files.
Requested credit card company to provide details of charge since personal Amazon account showed no such charge for the date of charge (or any other date, for that matter!).
Credit card company investigated and replied that Amazon did not respond to their request for information on the charge. Recommended that I ask Amazon for details.
When I did, Amazon claimed to have contacted the credit card company and that charge agrees with the records of the credit card company. Amazon recommended that I contact credit card company for details of charge.
I contacted credit card company again, and they told me that they "had no mechanism for going back again to Amazon" for more information on this charge, and they had no details on charge.
I suspect this charge is fraudulent, but now am "between" the finger-pointing credit card company and Amazon, with no resolution or response from either.