There are various possible ways to incorrectly send a transaction using cryptocurrencies.
An example is sending Bitcoin to a Litecoin address. Another example is forgetting to include a memo on a Ripple deposit. A more simple example might just be copying and pasting the wrong address while withdrawing.
This is not an exhaustive list of examples. Crypto sent incorrectly in this way may be lost and there may be no way to recover.
Depending on if you made a deposit or made a withdrawal would dictate who the best party would be to contact for support.
If you made a deposit where you had an issue, Metal Pay would be the best party to contact.
If you made a withdrawal where you had an issue, check to see the status of the transaction in your wallet, if the transaction hasn't gone all the way through, it might be possible to cancel it.
Once the transaction is broadcast to its respective blockchain the transaction is considered complete on our end. We no longer control the specific crypto and have no ability to assist once it leaves our wallets. You would need to contact the receiving exchange or wallet provider for further support.