seat belts dont lock

my seat belts dont lock when they're supose to. they will lock up when i'm trying to put it on but wont when i slam on the bracks at 70 or any other sudden stop. what can i do to fix this?

Take it to the dealer. Seat belts are lifetime warrenty of they don't latch or retract or even if the don't lock you in the seat then there is obviously something wrong with the mechanism.