Xperia C4 "ghost" touch and repair issue

[plantiff]

Hi, I had purchased SONY Xperia C4 from BestBuy during my visit to US on Jan,2016. The phone worked quite well for about three months and then started giving multiple touch issues. I tried all sort of solution such as factory reset, software repair etc.. but the problem seems to persist adamantly. Upon searching on the net i found that many model have such "Hardware" issues wherein SONY offers repairs. 

I contacted my local SONY service center in INDIA , but they denied repair service even though it is under warranty saying that International warranty is not covered. 

Now Im stuck with a defective but under warranty Xperia C4. I cant use the phone as multiple touch causes un-intended call and causes so much nusance.

Kindly can some one help me with the phone being repaired locally or is there any way SONY helps customer with internationally purchased products....

[Uliwooly]

@plantiff

I'm sorry to hear about your issue but the warranty it's only good to the country or region in which the product purchase took place. That's not just Sony but you can read about "Limited Warranty" on other brands and/or products, such as Apple

Here's an example

Back to your issue, does the phone has a protective case, film, glass? 

[plantiff]

Yes, my phone has a protective film (wet type). Installed around 3 months back.  But I dont suspect it as the film issue, because sometime the screen works for about a minute after unlocking the screen.

Do you want me to remove the film?

[Uliwooly]

@plantiff

Things to test

Remove the film and test it 

also

boot in >>> safe mode

I've seen a LOT of issues due to a film or case or protective glass. 

[plantiff]

I have tried in safe mode, but it has not helped

[Uliwooly]

@plantiff

Then you will have to remove the film

Also, do you have glove mode on?

[plantiff]

No. Glove mode is showing disabled.

[plantiff]

I have also noticed that the touch behaves weirder when mobile heats up. Is the touch digitiser defective?

[Uliwooly]

@plantiff

remove the film > boot in safe mode > settings > about phone > diagnostics > test > test touchscreen.

[plantiff]

I removed the film. started the phone in safe mode, but the touch problem is so worse that I am not able to go till the diagonistic tab due to touch issue. Either a single line vertical column or single horizontal line touch is detected or not even that.

(I had enable show touch, so im able to see the multiple points that is being touch activated.)