Hi neil6,
This does not have to be a cheat on your opponent's side. 

A game “freeze” happens and is common in an online game. Time/game freeze means either you or your opponent quit the game or lost connection. 

If your opponent's Internet connection is interrupted (regardless of the reason), remain in the game for about a minute - until your opponent's nickname is no longer visible. 
If you do so, the victory will be credited to you by the system automatically.

Kind regards,
John