Complex sentence: The managers of Fey created a controversy with respect to her age, they decided to put 17 years to her when in fact she had 21, situation that was not denied at the time nor by her managers and by the singer.
Split into simpler sentences: The managers of Fey created a controversy with respect to her age, they decided to put that she was 17 years to her when in fact she was 21. The situation that was not denied at the time nor by her managers and by the singer.