That’s awful!! Yeah, Poloniex was unnecessarily sketchy about the whole thing.
Right now the most reliable exchange is Bittrex INTL. If you’re in the US, however, you’re somewhat out of luck (although Changelly may work).
In terms of storing MAID, you may find this thread useful: [How To]: Buy/Move/Store OMNI MAID :safe: hardware and software wallets - #33 by Dimitar.