All I can say to your comments is that you have been very lucky and I think you must be very much in the minority in getting any sort of satisfaction from email responses.

My experience with this form of CS is that the email responses are generally not relevant to the query I have put to them as if they have a number of stock responses they give and they just choose the one that they think is closest to the one that might answer my question. Generally it doesn't.

I usually have to write back on 2 or 3 occasions with the same query (and pointing out to them that their previous responses simply didn't come close to addressing my question) before I get anything like a response that is appropriate or helpful in answering my question.

Routinely, I come away from the experience feeling dissatified and like I've wasted a lot of time for no real benefit !!