Unsatisfactory service and dishonesty

I usually buy lunch at KFC (Denlyn Mall). And they have a tendency of wanting to upsell the medium meal by force selling. They would say their soda machine is broken and they can only sell the bottled drinks. This means we have to upsize every meal we buy and pay more without choice. It's really annoying and I once told them I'm not leaving until they sell me my "small" drink meal, and surprisingly their machine started working. I'm very disappointed, I know they have targets to reach but dishonesty will make them lose their customers.