The transaction now has enough confirmations to consider it confirmed 100%.

You've sent BTC to an address that exists, so there's no room for the "you've sent it to the wrong address" excuse. The address you have indicated (12xYef9W528E1LqTRyjejFWWackwGEz6p4) has had a total of 1.72508121 BTC received, out of which 0.00816938 BTC (~$75) was received yesterday. This is the only funds the address has not spent yet, and that means the money is still sitting there.

Even if the address was empty and had 0 BTC in it, if it's the address he indicated then it's not your fault. He either has a wallet out of sync, is lying to make you send him another $75 or might've been subject of a phishing scam (clipboard virus) if he copied his address from PC and it's infected with such malware.

Anyhow, if your client said "12xYef9W528E1LqTRyjejFWWackwGEz6p4" is the right address, you have done your job the right way and have nothing else you can do except showing him the txid.