I am not the PO but no, Cryptopia is an exchange. Users dont have access to private keys.Does the Cryptopia wallet give you access to your private keys?
How how is a big payment for you? I have made fairly large bitcoin payments. I exercise the same precaution as I do with all my BTC payments. I make sure the address is correct and I am paying the amount I intend to pay.Have you ever payed big payments in Bitcoin? Is there any risk