I drive a 2017 Creta.

After a service I noticed mousture spots behind the plastic display of my car's dash.

I took it back to the dealer where I was told it is something I sprayed from the outside onto the cover which has corroded the plastic cover. I was dumbstruck as it is obviously on the inside of the display. It was not like this when I took the car in for the service.

I am now left with dried watermarks on the inside of the dash displsy. What can I do? I read up and it seems like moisture could get into the display if it is not sealed properly.

 

It sounds like a logical explanation and it does happen if someone gets carried away cleaning the display.
The big question is when it happened.

 

Thanks for your response. I noticed it the evening after my car was serviced as I turned on the head lights

 

You know how this works, your word against theirs.
You need to be able to prove the dash was OK when you brought the vehicle in there.
A good session with the service manager may just come up with a solution that is acceptable to you both.