Are you sure he successfully made the transaction? And the wallet address of the receiver is BTC not BCH right?
Is this blockchain wallet address, isn't this?
It means that your transaction is not confirmed, I think if this is not confirmed, he can cancel it. but, better to contact the support at first.
If it is said pending , it is also probably about the transaction fee that is too low and he needs to increase the fee, see on details, and of course, ensure that you get the proof of the transaction. Ask the sender about the transaction and the fee.