U2718Q, image retention

Hi

I am really devastating and exhausted about image retention. I bought a new U2718Q about 7-8 months ago (December 1, 2019). It's needed only 3-5 minutes to "ghost" image to appears and then it stays for hours. I asked official technical support and they replayed to me they will change the display, but a few hours later they changed the decision and said in a really rude way - it's not a warranty case.

I've already tried all of the following:

- LCD Conditioning (Menu -> Others)

- Display Factory Reset

- Changing HDMI cable

- Running display with MacOs and Windows computers

Unfortunately, it had no effect. Is it a real display problem? Should the default warranty work for this case?