The Barca attacker defended his parents for making millions on his move to Barcelona and ranted after his father was branded "a jerk" by a former club chief.
The 22-year-old left Brazil officially for 57.1 million euros, although figures released by the Catalans last month suggest they forked out 86.2 million euros for the summer transfer.
Current Santos chief Odilio Rodrigues has been extremely critical of Neymar's father for pocketing 40 million euros of his son's transfer fee and the club has started legal proceedings to see the documents behind Barca's agreement with the forward's father.
Former club president Luis Alvaro de Oliveira Ribeiro (commonly referred to as LAOR) chipped in by branding the man "a jerk" on Wednesday, saying it was right to take "people like him" to court.
This was a step too far for the Selecao attacker — back in Barca's squad following a month out with a sprained ankle — who ripped into the Peixe hierarchy while defending his parents' company, N&N, for making money on his move to La Liga.
"Once again I am taking the liberty of speaking of a matter that has gone over the lines," Neymar wrote on his official Instagram account. "Today I understand why my friend Ganso didn't stay in Santos: it wasn't because he didn't like the club or didn't want to play for Santos, but because of the board of directors!
"I always respected all of them and I have been extremely professional. I'm utterly disappointed with former president LAOR and the current one, Odilio. But mostly LAOR, whom I have always treated with utmost affection and admiration. Today all that is gone after the things he said about my father. I'm sick of that, all that talking is getting on my nerves! If he thought my father was dumb, he was wrong!
"I'm a fan of my father and I'll continue to be for having taken me to where I am today and if he made millions over that, what's the problem? He worked, he didn't wait for anything to fall from the skies. I'm done with them. I'm sorry Santos fans, but two people will not make my affection for Santos go away."
Meanwhile in Spain, it emerged Wednesday that prosecutors are alleging that the Camp Nou club dodged paying 9.1 million euros over 37.9 million euros of undeclared tax over the Neymar transfer, although Barca issued a statement defending its actions.