Kind of feel like I lost out

I bought a 5-piece fried chicken from a convenience store. I usually don't buy it because it's expensive. This week, there was a limited-time discount coupon, so I thought it was a chance 🐔 and went to buy it. Getting 150 yen off felt like a good deal 🉐 I also bought some city-designated garbage bags, which I had run out of. When I paid, I thought, 'Huh? Isn't the price a bit high?' Looking at the receipt in the car, I was shocked 😱 It was a 130 yen discount, not 150 yen. It was a complete misunderstanding. Even 130 yen off is a good deal, but I was mentally prepared for 150 yen off, so I was very disappointed ↓ It tasted good, but I still feel like I lost out. I really need to check things properly 😰