PEUGEOT 406 Airbag Center

Hello, I have a Peugeot 406 2.1 STDT of the year 1998, I was going to pass the ITV and they have thrown me through the witness of the airbag of the driver that blinks, I have asked for opinion in several workshops and in the end I have taken it to the house, I have been told that it is the airbag, that this broken, could someone tell me how to change it? Or if it were another problem, I don't know what to do, I have 54 days to do it, and if you don't goodbye car, or pay 550 euros to do so in the Peugeot. I help please is the very bad thing.
Thank you

If it is indeed the switchboard it is better for you to take it to the house because if you do and do it badly, the airbag will be activated and you will have to buy them and there if you get out they are very much.