I dont know man but to remove airbag it self you have to poke and when you feel that you have pushed the spring then bend it up and the side wil pop up, do the same thing with other side and you are done.
However i have never heard or seen that the front of the airbag can be replaced !!!

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X5 4,4i-06 Current
330Ci Cab-03 2007-2008
MB E55 AMG-03 2006-2007
Z3 2,8 Roadster-98 2006-2007
X3 2,0d-05 2005-2006
320d-99 1999-2005