I bought a very strange iPhone 4 Proporta screen cover at FNAC but because I already installed the phone, the store does not refund me now.
I contacted Proporta via their website and twitter account and in less than 30 minutes I had an email from them:
Thank you very much for your message today, and for your comments on Twitter.
The way the screen protector is manufactured may create the a strange rainbow effect on the screen protector when held at an angle. However if you are not happy with this item then we can offered to exchange the Screen Protector for you for one of our Clear Advanced Screen Protectors.
Now that’s costumer support!