nissan micra 5 door 57 reg. ?

i have a nissan micra 57 plate 5 door ,and the air bag warning light keep coming on. i have taken it to the garage 3 times and they removed it ,but it keep coming back on. i was told i need a new seat belt stork or holder (the red bit the seat belt clips into ) how can i remove the light myself at home . its is driving me crazy plashing all the time. please help.thank you