Unfortunately I cannot tell from the photos what those "stains" are. I know it is very difficult to take good clear pictures of display related issues due to the highly reflective glass. Only someone who can examine the laptop first hand can tell what those "stains" may be. Even then, they may have trouble identifying the cause.
In my opinion that does not look like the typical anti-glare coating "staingate" issue. I've seen a lot of the "staingate" coating issues over the years so I am quite familiar with Staingate. Just from what I can see from the pictures it looks like the screen needs to be cleaned & buffed, or it may be liquid damage where liquid has gotten between the glass & the LCD Panel. The "bubbly" nature of the "stains" looks a lot like what I've seen from a liquid damaged display. Keep in mind this is only my assessment from reviewing the photos which are not very clear....only an in person inspection can do a proper assessment. I'm just trying to prepare you for the possibilities.
Do you see those issues when the screen is showing an image? Best to use a plain solid color image, especially a white or light color? If it appears as bright & dark spots, then it would make liquid damage more likely.
Best case scenario it is just a misty layer of "grime" that can be cleaned. I prefer to use an LCD screen cleaner to lightly dampen a very small clean section of a microfiber cloth to clean the screen, then change to a clean dry microfiber cloth to buff the screen clean....you may need to use another portion of the dry cloth to continue buffing with a new clean section. It is critical not to let any liquid get near the edge of the glass, or it can seep beneath the glass.
Also, I've never worked with a laptop with the nano textured display so not sure about an LCD Cleaner or whether any microfiber cloth is safe to use since Apple's articles very specifically mention only using the Apple factory supplied cloth.
FYI, when @KiltedTim mentions screaming.....that is when someone writes in all upper case letters. Plus all upper case characters are very difficult to read. Also, it is best to add an empty line between paragraphs (aka "sections" to make it easier to read. Notice how I wrote my reply here.
As @KiltedTim mentions.....I have also seen similar complaints regarding Apple service in India. If you cannot get a proper assistance from an Apple Store or Apple Authorized Service Providers (make sure to politely talk to a manager to attempt to attempt to resolve the issue), then I would suggest contacting Apple directly starting with the closest regional Apple corporate office (if any), then to Apple corporate in US if still no satisfaction. Such issues should be reported to Apple corporate offices.
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