Double charge single meal.

KFC Drive Through swiped my card twice. In the first I show the server my cell phone to verify the amount went through....But she insisted that it does not reflect on her side. I queried a few days later...and a kind lady confirmed the tractions was done twice. Please provide some guidance to the window servers as it's causes a bottle neck in the queue while the server room is sorting out this issues with supervisor and other teams members.