P2415Q, exchange for broken

I am from Russia. I have P2415Q with grey lines on screen. I read few topics here and contacted Dell support. They instructed me to leave my monitor in one of authorised partners of Dell nearby. Which I did about two weeks ago. Now they seems to refuse to make an exchange as they don't confirm the monitor to be defected. But I can easily demonstrate the issue, also I've sent photos of the issue during our E-mail conversation. Can someone help me to get my monitor replaced?