Appendix 1 says “The action of the striker who strikes, or is in a position to strike, the ball to the right of the body after the ball has passed behind it to the left or vice versa, whether the striker physically turns or not.”
The important point to note is that the ball must pass around behind the body from one side to the other. It does not actually matter if the player turns or not.
You must not hit your opponent with the ball when you have turned – you lose the rally if you do! (Unless the opponent deliberately jumped in front of the shot!)
You should ask for a let if in doubt of your opponent’s position, but there is no rule that says you cannot play the ball when ‘turning’ occurs. And a let is not automatic either if a good return was not possible when the turning occurred, that is, you had to be able to get the ball back to the front wall to get a let.
Nor are you allowed to deliberately create a ‘turning’ situation in order to create a let – a tough one to rule on.
Turning situations can be tricky to deal with, but safety is paramount in our game, and turning can be dangerous. A player who turns and plays the ball near their opponent should be warned against their actions if dangerous.