Which coin are you talking about exactly. It's obvious if you deposit shitcoins then that would take a very long time to reflect in the wallet.
I have been using cryptopia for quite a long time now and it has never given me trouble. There was a deposit issue once but once i mailed them it was solved within 24 hrs. The withdraw charges are a little bit more than other exchanges but then it is not too much. If you want to transfer the coins between exchanges then you should buy coins like Doge, DGB, XRP etc.. and then transfer them to other exchange and then convert them back to BTC. This will save you the transaction fee