Hi everyone, Cryptopia has not contacted us before making this decision.
We are trying to reach them to get more detailed information about it. Also we are going to offer them fairer and less drastic solutions than delisting the currency straight ahead.
We'll keep you all updated!
I think your should better switch to PoS or PoS/PoW to fight double spend attacks. Otherwise double spend issues will rise again and again.
And if you are not a scam, please make an effort to list yourself on Bittrex (but you might need to solve your double-spend vulnerability before listing).