Dear John: For more than three months I have been involved in a fraud dispute with Citibank Mastercard for the amount of $45,500. There were six consecutive fraudulent charges of between $7,500 and $8,000.

Citi has given me the runaround, pretending to investigate these unauthorized charges put through Square, an internet service, to my Citi Mastercard.

No one received the funds, and I did not authorize the charges. But Citi Mastercard is now holding me responsible for payment.

These charges triggered no security alert with Citi Mastercard, and I did not receive the usual emailed receipt from Square.

I contacted them to report fraudulent activity as soon as I saw the charges on my account.

I believe Square was hacked, because no one received the funds, and I did not get the receipt.

If you would like more details please contact me.

Thank you for your service. L.P.

Dear L.P.: No, that’s quite enough information. As you know, I contacted Citi — the right people, apparently — and the matter was resolved in a day.