I flew from JFK to CPH on Delta Airlines.

The trip wasn't a long one, but I needed the Medallion Dollars to keep my Diamond Medallion status, so I went for it. I will be at just over 15,000 MQDs for the year after flying this trip.

There was a mistake in Delta's system. It would have cost me my status if the mistake hadn't been noticed.

Delta credited my account even though my ticket cost nearly $1,000. I didn't think I'd earn MQDs on all of that spending, but I knew something wasn't right.

DELTA.COM

I checked an elite status tracking spreadsheet that I keep and found that I should have received more than 800 MQDs for my JFK-CPH- JFK itinerary. The ticket had a base price of $266 and a surcharge of $600. My missing 273 MQDs have been brought to my attention. I was shorted more than 3000 SkyMiles as my mileage earnings were calculated on the wrong base fare and surcharge.

This story has a happy end. I explained the situation to the person on the phone. He called the SkyMiles department, they noticed their error, and the representative told me they would calculate earnings with the correct fare and surcharge.

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My account was credited with the correct number of MQDs and miles around an hour later.

DELTA.COM

I could have lost my Diamond benefits if I had not noticed the error. I would have had to book a flight after I realized I did not qualify for my status. It wouldn't have been cheap to do that after the holidays.

You should audit your loyalty accounts.

After you fly, make sure to check your loyalty account. Make sure you get the correct number of miles and metrics. You can leave elite status on the table if you don't.

I encourage you to keep a log of your flights. All of my flights are added to this spreadsheet as I book them. I have a number that adds all of them up and adds them to my balance. It helps me plan and audit my account quickly as I travel throughout the year, and it keeps me up to date on how close I am to the next elite tier.