underlag garanti

You can check your AppleCare coverage and warranty options by following the steps here: View your Apple devices and AppleCare plans on My Support - Apple Support

You can also see if you have coverage here: Check Your Service and Support Coverage - Apple Support

I don't think that you get a paper receipt, but you could contact Apple Support and see: Contact Apple Support

You're going to have to explain what 'garganti' is, as well as what you mean by 'backing' if you want support.