Sonic Drive-In

My grandson and I went thru drive thru and ordered what we wanted I told the guy I had a gift card to use with the order, when they came out with the order the lady had a new gift card which I did not ask for took back and got the money for it but the gift card we had for partial payment was not used. I still paid the amount of 16.59 it should have been 6.59 but not the case I will never go back to sonic again. I want all my money back.