usually if you purchase INSURANCE there is a clause where a replacement will void the insurance and you're no longer covered. however this should not apply to manufacturer warranties in my experience. the 90days clause from the rep who was 'off script' probably applies to accessories, they recieve 90 day warranties for headphones batteries etc.

this said i'm in the uk and they definately would not get away with that here, actually a little known fact in the eu any electrical devices sold should be fit for purpose for 5years from the date of purchase, so with a little research and well worded correspondance free out of warranty repairs are possible.

moral of the story, check BEFORE smashing your phone!