"Which way did they go, Peeves?" Filch was saying. "Quick, tell me."
"Don't mess with me, Peeves, now where did they go?"
"[A] Shan't say nothing if you don't say please," said Peeves in his annoying singsong voice.
"All right - please."
"NOTHING! Ha haaa! [B] Told you I wouldn't say nothing if you didn't say please! Ha ha! Haaaaaa!" And they heard the sound of Peeves whooshing away and Filch cursing in rage.
–– Harry Potter and the Sorcerer's Stone
It seems to be [B]’s highlighted part isn’t a remoteness expression but a backshifted preterite from “I won’t say nothing if you don’t say please.” Does Peeves use won’t in [B] to denote semantic difference from [A]’s shan’t?