Cape Town - Frans Steyn's dad has confirmed that a broken promise from the South African Rugby Union (SARU) was one of the reasons his son left the Springbok squad.Click HERE for more FRANS STEYN newsSteyn, 27, shocked the rugby fraternity on Tuesday when he pulled of out the Boks' Incoming Series in June.It was reported that Steyn left after a dispute over money with SARU.Piet Steyn told Thursday's Die Burger that SARU did not adhere to a contractual promise they had made to his son.The monetary promise was made by SARU before Steyn returned from French club, Racing Metro, to play for the Sharks in 2012.However, Steyn Snr made it clear that money was not the only reason behind his son's decision to pull out. He said there were "other issues" that cannot be disclosed."If it was only about money, then Frans would never have returned from France to play in South Africa. He is in top form and is playing some of his best rugby. He has matured and makes thoughtful decisions."He said Frans is very emotional about the the whole situation because he was very proud to have worn the Springbok jersey.Frans will finish the Super Rugby season with the Sharks before heading to Japan. It remains unclear when he will again be available to represent the Springboks.