Stripes Appeared on the Screen of My ASUS TUF Gaming Monitor

I have an Asus TUF gaming monitor, and the screen is acting up. It's showing stripes and becoming unusable whenever it detects certain colors. I submitted a repair request on the Asus website, and they approved it. After getting approved on December 4th, I followed their instructions and packed the monitor. I made sure to include the warranty document and the invoice. They were supposed to come get the monitor in 2 days, but for the past 2 weeks, I've been dealing with Asus. Whenever I reach out to customer service, they always give me the same reply: "We're making it go faster with UPS." I've called four times, but the monitor is still at home, waiting for the courier that never shows up.