Black Smudges growing on Screen

A while back a series of black stains appeared on my imac screen, which grew.
I took it back and they changed the screen, now with the new screen the same thing is happeneing. Im gutted, I love my iMac but this is crap.

It starts out as a small shadow and grows over the months. Ive been told to take it back but am worried it will just happen again as its only been a month since it was changed.

Has anyone had a similar experience?

cheers

I believe Apple will give you a brand new machine if they can't solve a problem within a certain number of attempts. I believe it's three, but I could be wrong.

Take it back every time you have an issue. That's why they are there. They want your repeat business. They will get you fixed up.

heres hoping for the new imac then.

thanks, I will take it back asap