Kentucky Fried Chicken-Long John Silvers

We like going to KFC once in a while for the $ 5 fill-​ups. I generally see them as a more expensive fast food chain and only after this offer was presented did we start going.
This particular KFC location seem to be lacking some costumer service. I’m general, regardless of your rules and restrictions, show some goodwill and some generosity that I promise will not ruin your business.
Today we went and got two five dollar fill ups with mashed potatoes and bought an extra side of mac and cheese. When our order came out we saw what was a tiny side of Mac and cheese for $ 1.59 and two half empty mashed potatoes. We asked them if they could actually fill them up. They wouldn’t do it!!! I have never experienced such costumer service, even at McDonald’s where the price tells you not to expect much, you get free cokes and extra fries if your order is messed up.
Please KFC, pick it up. It isn’t asking much and you would come along way with that extra 5 cents it would’ve cost you to fill up cup