I never got a response

I was going to bid on a set of coins 'graded' (huh) by SGS. I sent them a question through EBay to the seller. I asked them how long they had been around, if they were registered with or affiliated with any reputable grading service or numanistic establishment. I wanted to check what kind of records they had of their grades. Sent the same e-mail to 4 different sellers. No reply from any. Sent again, still no reply. I mean do not get me wrong, they look nice in the holders, and they are worth more than a raw coin. But for a company who produces such high grade certifications, you would think they would be proud to display the results.