Nescafe 2-In-1 Spoiled Product Issue - Sour Taste And Defective Sachets

On October 31, 2025, I bought a 10-pack of Nescafe 2-in-1. The expiration date on the package is 05/2026. I buy this product from the same market twice a week and have been drinking it every day for years. As soon as I got home, I made a coffee, and with the first sip I realized the taste was awful—bitter like poison, spoiled, and sour. To be sure, I tried the other sachets in the package, and all of them were spoiled in the same way. It tasted as if someone had squeezed lemon into spoiled milk and then added coffee. I contacted Nescafe customer service and explained the situation in detail. However, they told me that I must have prepared the coffee incorrectly, used limescale-heavy water, or didn’t get the temperature right. I worked for 15 years in the cafeteria of a major hospital making and selling thousands of coffees a day, and I’ve been drinking the same coffee at home for 20 years. Their explanation felt both illogical and belittling. Moreover, the entire product was spoiled, and that is not my fault. I bought it for ₺89. I may not have the receipt, but I have the expiration date and market information. I am requesting either a refund or a replacement. I want my issue resolved.