Poloniex isn't perfect nor is any exchange. I doubt anyone will be able to say, in the near future, that they have never had any problems with bitshares. Seriously, if you switch exchanges as quickly as you change clothes then you will never be satisfied. If your exchange slips up a few times, then you should excuse their technical issues. Consistently stand behind one exchange collectively or this entire market will loose credibility. However, if Poloniex hasn't responded to you at all. Then by all means, screw them, there's no excuse for that.