Royal Caribbean complaint: Fraud charges

Hello,
My husband. myself. a friend, and other friend went on a cruise with Royal carribean. We left Los Angeles on Oct 30th. After leaving we received an emailinvoice of stay showing a charge saying we went on an excursion. We did NOT book, nor agree to pay for any excursion. In fact we left on foot, paid cash for the shuttle to take us downtown to walk the streetsshops then returned. Our friends went with us and did not get this charge but we did. When I contacted Royal carribean they sent me a copy of the “receipts” showing an excursion. However, they are not signed by anyone in my party. Again, we did NOT book, nor agree to pay for any excursion, nor did we go on one. They refuse to reimburse us saying we did book and didn’t cancel but we didn’t. I have requested proof (videos, signed receipt- real proof we booked and went on an excursion). We have friends who were with us who can attest to the fact we didn’t. I don’t know who else to file this complaint with? It’s not a large amount but at this point it is the principle and it is fraud.