Beware of bait and switch!

Beware of bait and switch!
I ordered a two scoop cup for my two grand kids to share as one scoop is about $5 and two scoops is about $7. After putting the two scoops in one cup they asked if I wanted a second cup. Sure I said. So he pulls off the top scoop and puts it a second cup. I pay with cc and walk away but notice I got charged for two single scoops!
I was unable to get a partial refund despite my argument.
BTW, the price does not show up on the credit card reader. Makes for convenient overcharging I guess.