How do I find out what a charge is for?

I have a charge for $13.49 on my cc statement, but I don't know what this is for. When I go into my account in iTunes to check my apple purchases, that amount is not listed. Also when I go into my iphone to Settings>Apple ID (at top)>Subcriptions or Purchase History - this amount is not listed anywhere.

Also called the 800 number and get the robot at Apple which sends a text link to the same info as above, so not helpful.

How can I contact Apple to find out what this is?

Thanks!