Maradyne Corporation — unauthorized visa charge

Charge of $21.88 turned up on Corporate Visa credit card statement, only description was for Amazon mktplace pmts amzn.com/bill wa.
I would like to know what it was for and who in the organization could have charged it as the President of Maradyne who is the major card holder has no knowledge of this transaction.

Could I have a telephone number or email address of any one at Amazon who could help me.

Thanks

Donna Gore
Maradyne Corp
[protected] ext 118
[protected]@dcm-mfg.com