The ethereum network faced some major issues lately so it's very likely that the exchange isn't at fault here but likely the currency's infrastructure. Be a little patient and staff of the exchange will likely review your issue if you're persistent. Poloniex doesn't have a reputation of being scammers.
Noone gets the reputation of being a scammer before actually becoming a scammer!
Hmmm... They were hacked and they returned the money to the customers in 2014.
I bet Poloniex has less than 5 people working (excluding the moderators of trollbox that have been transfered to other positions).
They make a lot of money on transaction fees on daily basis so rationally it is in their best interest to act well. They have a lot to lose.
Personally I have not had any serious issues with Poloniex (although the site is a bit clumsy).