In this case, reply to the email you received from Coinpayments about the expired order.

The mail is: [email protected]

Here you have a template that you can use:

Dear Support,

I paid for an order, 

CPID / LINK TO CP ORDER PAGE

And the money reached, transferred onwards, not automatically and not via refund method. It was paid and it completed but I did not get a refund mail for the excess/ failed transaction

I enclose the blockchain transactions showing the funds reached the order address. Order settled in [WRONG COIN.NETWORK] instead of [CORRECT COIN.NETWORK]

Txid

PAYMENT HASH FROM EXPLORER PASTE

Please could I ask you process it back to me so I can recover the failed payment if possible.

Thank you

Regards