I've similarly had terrible experiences with poloniex before, with all the awaiting approval withdrawals to laggy interfaces.
I haven't really used them ever since their legacy account system was completely wiped out and you now had to verify yourself before you can actually deposit, trade, and withdraw within the platform. There was simply no point, as the only advantage that they held over other exchanges at the time was convenience and anonymity, which is now gone.
I'd say that they haven't really improved by that much because of the fact that I've seen people still complain about the speed of their customer service (which has always been extremely bad), and constant issues. I would recommend you not to return to using them.