Hungry Jack's

I have only been to this store a few times and never had a problem until today (drive thru)- my order amounted to $21.40 which was incorrect. When I opened my order they had added an extra chips and coke which accounted for the high price. I alerted the assistant to the error and was then given the correct order, however the refund didn't seem to reflect this. I was only given a refund of $3.40, which means that a large Whopper with cheese meal and one extra chips amounted to approx. $17. I assumed a receipt would be in the bag, unfortunately it was not, so I don't exactly know how much the meal deal was or the extra bag of chips, as each store charges different prices. Doubt that I will be returning to that store again. Robyn