This is not permissible. Only if the customer knows or the man was authorized by the manufacturer then he can do this.

A middleman opens a website with his own brand, he has an agreement with the wholesaler(other brand) that he will find retail customers for him. Middleman sets his own retail price on the website. The customers come directly to the wholesaler, buy the product on pre-agreed price, middleman gets his commission after that. Is there anything wrong with this scheme like selling what you don’t possess?