If it is confirmed on the blockchain, the money has been received. You can crosscheck with any blockchain explorer (example) but if your wallet shows it as confirmed, you know it has been received.
If the recipient disputes this either they are lying, incompetent, very inexperienced and mistaken or gave you the wrong address.
Since addresses have checksums, money is very unlikely to be sent to a mistyped address, your wallet would normally be able to tell you if a receiving address was somehow mistyped.
If the recipient is a crook, sending them proof won’t change their behaviour.
