Greetings from Down Under yet again.
Today in our club competition, a player unknowingly played a wrong ball on her second shot all the way down the 5th… (2 stroke penalty?).
After teeing off at the 6th and addressing the ball for her second shot, she discovered and declared that she was playing a wrong ball. As she liked this ball, she continued using this ball to the end of the round.
As usual we have had so many opinions as to penalties incurred.
What is the correct ruling please?