Poloniex has a HUGE backlog of tickets they're working through. Someone of reddit finally got one resolved that he'd opened in June!
If you arn't making any headway, make a reddit account and then send a private message with your ticket number to
https://www.reddit.com/user/Mike-PoloniexOP's problem is resolved, but this post is very useful for further issues. The issues of the second half of this year seem to be solved on poloniex, so I went back with my funds. I personally didn't have bigger issues, but there where so many threads here about issues there and they had many DDos attacks. But now its working fine.
Pending deposits on XEM seem to be caused by network, not poloniex.