Out of curiosity, who's he saying the COA is from? You have two things you're trying to validate here - whether the autograph is authentic and whether it's actually game used. I'm guessing the latter will be trickier.
It's a personal company COA as this was given from a close friend who received multiple items from several Colts players during the 06-07 season. That's what they told me.
It's his friend's company's COA? Or a COA he made himself because his friend gave it to him? I think the next things you'd ask for is an image of the COA and info about this friend and how he got game used equipment. If he can't answer those questions, it's not even worth considering (honestly, given what I've seen from this seller, I wouldn't even consider him anyway).