poloniex in trouble?

Some time ago i opened a trading account at Poloniex. I sent some btc.
It's never arrived to my my account. I'm pissed.
I made a ticket at Support. I'm still waiting for a response.
I'm so pissed.
I checked Poloniex twitter account, and a few days ago they posted that they have been under a continuous DDOS attack.
Anyone thoughts on that?
I want to get some altcoins. Obviously it's not going to happen at Poloniex.
Anyone has any advice as to which platform is actually safe ..and responsive??