I have known this company for a long time and they have never disappointed me, I dont know the issue you are having with them , but has not really affected majority of people, your experience with them might be a bitter one, but it is not enough to pull the crowd along in your decision.
What if it was just a simple technical issue, we dont even have the details of your real challenge for us to follow your advice, the only challenge you have mentioned here is your mail not being attended to, maybe you should push a little further, Facebook once did something of such to me because of many client on queue for them to attend to, but I had to push a little bit more till the resolved my issue.
If I wasnt patient then, I would have probably come on one of these threads to tarnish their image.
Funny enough, I just read in a place not quite long on this same forum where we have many people that has praised the service of coinbase, many people with different experience and different opinions, I think it would have been clear to the OP too by now that he blew thing out of proportion after seeing the number of people that has got good experience using coinbase.
Like you said, patience is sometimes a virtue, it might just really be a minor issue, but because of his temperament and impatience, ran to the forum to quickly destroy their image, but unfortunately, he got the reverse.