It is recommended by Silestone.com that hot pans not be put directly on to the surface, and, that you use a trivet. So I guess it is unfortunate that this has happened. I don't think that moderate heat includes a pan straight from the stove as that would presumably be classed as 'red hot'. I feel very sorry for you, but it is down to the consumer to know the product and use it accordingly, Silestone can be marked, and scratched too, so i guess be more careful. Such a shame. Here's their literature on care, which I think personally you should have been given at the time of installation. Silestone

You can put hot pans on Granite..............my wife does it quite often if she runs out of room on the cutting boards. However, for the most part we do try and use the cutting boards in preference. Our granite has been in situ for around 15 years and still looks like new.

Playing devils advocate, I think you need to take some responsibility here. Did you read and familiarise yourself with the manufacturers post-installation literature? There would have been some - even on their website. If the info is available and you have not given heed to the recommendations,, unfortunately, it's down to you. Common sense tells you not to put hot pans directly onto kitchen surfaces.