Hello, I have for 6 months tv panasonic TX-55CX400E a few days ago I appeared 3 dark spots on the screen below on the photo you can see what's going on:
what's the best I sent the tv back to the panasonic website and today they called me that they test it a few days and they don't have these spots, so I have no idea what these spots are about? please help

what's the best I sent the tv back to the panasonic website and today they called me that they test it a few days and they don't have these spots, so I have no idea what these spots are about? please help