7-eleven 7-11, 7-eleven Over charge for fountain drinks niles Illinois

Returned to 7-eleven to purchase a refill for my Big Gulp fountain drink.  Brought my previous purchased empty Big Gulp cup into the store, refilled it and went to pay.

The lady attempted to charge me 1.29 for the refill.  The price for a new Big Gulp is only 79 cents.  I couldnt understand why she is charging me more for a refill than a new purchase.  

She said she does not look at the cup, only charging me cause I said "refill", so she charged me the refill price.

I asked her if I tried to refill the Double Gulp (which does not get refills at the 1.29 price) if she would look at that cup, or only charge me 1.29 because I said "refill"?

Then she gets upset and tells me that I am cheap!!!  Hahaha, why because I would not let her rip me off???

I will never go to this 7-11 again.  Since this incident others have told me that they brought winning lotto tickets there and they dont give them the correct pay out.