If someone assaulted me physically and I was unable to retaliate, is it permissible for me to send someone to hit him on my behalf, acting upon Allah’s saying: {So whoever commits aggression against you, aggress against him in like measure as he aggressed against you}?

Whoever has been wronged and wishes to seek retribution from their oppressor, must refer the matter to the Sharia court; otherwise, they should be patient. As for sending someone to beat the oppressor, it is not permissible for two reasons: firstly, retribution is not exacted except in the presence of the ruler or his representative, and secondly, advocating for such an act would lead to the spread of evil and chaos among people.