I once had some windows fitted with a 16 year warranty, the company went bust after 2 years.
Thinking i had got it sussed, when i had the sofits refitted, i insisted on a insurance backed guarantee, unfortunately i didn't go into fine detail, i got the insurance, but some years later when the white down pipes became beige, i thought to get them replaced under the insurance, the rub was, if the call out was in there opinion unfounded, then i was to pay for any call out, the the real body blow i had not foreseen was the first