Sonic Drive In Paid more for item that is less than 7 bucks New Iberia, Louisiana

I don't usually eat fast food, but on a Friday night I decide to treat myself. I bought my little brother with me we went to Sonic drive In. I bought an M&M and Snicker Sonic blast the total was $6.47. I don't usually carry money so I gave the employee my card. She couldn't use the machine outside so she had to use inside one. I got my card back but no recipe I didn't think anything at the time. When I got home I usually like to check my bank balance. I notice i was charge $14.71 for something that only cost less than $7. I called sonic and talk to the manager she took my name and number down and said that she would give it to the General Manager. Supposedly, the GM would call me on Monday but I still haven't heard from them ....