Marathon Gas

Well Marathon gas station, you lost a loyal customer tonight. I have been using this gas station for the past two years and have always been impressed by the prices and the quality — inside is a fully functional Dunkin Donuts and a pretty nice little convenience store. Despite the location I always thought it was a pretty great gas station, clean and big. Unfortunately I had a bad experience today customer service-​wise and I will never be going there again. I really wish this had happened AFTER I filled my tank as I don’t want this gas station ever getting a penny from me again.
Pretty much verbatim, this is how it went down: I went inside to the «Radiant Food Store» to get a soda and saw a deal for 2 Mountain Dews for $ 3 (a common deal at most gas stations). Screw it I thought, I’ll get both of them. Went up to the counter and was charged full price for both.
Me: Isn’t it 2 for $ 3 here?
Clerk: No.
Me: (doesn’t say anything, watches him bag them up). Oh… so the deal isn’t right? There was a sign that said 2 for 3.
Clerk: (angrily) Do you want them or not???
Me: (wants them. swipes my credit card and waits for him to accept the card.)
Clerk: (again, angrily) What does the card machine say???
Me: Um… it says «wait for cashier.»
Clerk: (does nothing.)
Me: So… should I swipe my card again?
Clerk: (stares at me and does/​says nothing. I swipe my card again.)
Me: I hope your day gets better! (Runs away)
Dear Marathon clerk, I’m sure you’ll never read this, but even though I didn’t give you any problems, half the people in Tampa WILL if you don’t honor a stated deal, or at least give an explanation as to why you won’t instead of saying «DO YOU WANT THEM OR NOT.» I’m sure you had a crappy day, but we all did, and that’s no reason to rip off a customer AND be rude to them. Although I acted like I had no real issue with you, I will in fact tell all my friends (who live close to USF and use that gas station every day) to never use your gas station, convenience store, or Dunkin Donuts again. I personally also work in a customer service field and I know what it’s like to have a customer who disagrees about price. News flash: you either give them the price they request (if they are correct, and I was) or you politely explain why they are wrong. You don’t give them an angry ultimatum because people might not remember great service, but they sure as heck won’t forget BAD service! I know it wasn’t a whole lot of money, but a good attitude means a lot. And don’t advertise a deal right next to a product if you’re not going to give people the deal! REALLY, SO SIMPLE.
What a disappointment. I will never be back here again and I hope you learn how to treat people before you lose even more business in the future.