We stand by all of our products quality, therefore it is only natural that we offer a two year warranty on all our stainless steel fasteners. If something fails within that time, get in touch and we'll look into it properly.
We will ask a few questions - how they were installed, what environment they're in, what tools were used. Not to catch you out, but because the answer usually tells us exactly what's gone wrong and how to fix it.
If you're ever unsure about the right grade for your application, ask before you order. That's a much better conversation to have upfront than after something's failed.