Dealer forgot to give change

[mathemagician54]

Playing 1/2 nl live, someone raises to 12 i call by throwing in 15. Dealer deals flop, original raiser bets. action on me, i say "uh preflop raise was to 12 right?" dealer agrees, then i say "you never gave me change..." then dealer says "it's too late." Is this correct? If so, at what point is it not too late to correct the mistake?

it seems silly that it's "too late" because it's a trivial matter to figure out how much is in the pot and how much should actually be in the pot.