Hungry Jack's Australia

I ordered a cheesy, bacon loaded fries and a frozen drink. I was charged $6.95. I asked the woman at the drive through window if the loaded fries are $3.95? She said yes. I then said and the drink is $1. She then had a look at the till and said yes. So I said should it not be just less than $5. She looked at me quite shocked and said no. I was still holding the $3.05 change she had given me thinking she would have realised the error but she didn't and the queue was building up behind me. I am not happy being short changed. I gave her $10 and got $3.05 change.