Outback Steakhouse

I drove up for curbside at OUTBACK within about 3 minutes a girl came out with my bag of food. It totaled 35.18 I proceeded to hand her a $4 dollar coupon that I got in the mail & I showed her a $10 promotional gift card that was on my phone. She then took my coupon, took my phone and my credit card and disappeared for at least 15 minutes. I wait in my car wondering what was going on why is it taking so long, finally I gave a few more minutes then got out of my car & walked in side Outback. As soon as I walked in there was a manager there along with the girl, I said what's going on, the manager then said "oh don't worry we're not doing anything with your credit card" and then the manager said they had trouble doing both the $4 dollar coupon and a $10 promotional card at the same time. Time on the originals receipt was 12:35p when I ordered. I drove up at 1p & signed final receipt at 1:18p.
How is original bill $35.18 & final charge $20.13, I only had a $4. coupon & $10. promotional card off=$14. (Not $15.05 off).
I am upset that they took my phone & then they took over 15 minutes to charge my card, while I sat in my car waiting & my food was getting cold.