Honda Jazz 2005

these are major safety items and especially the air-bag should only be fitted by authorised technicians, but the seat belts you should ensure you have the correct grade of bolts used

stick the wife in for a airbag replacement, also she can do a bad impression of a GPS

I agree with Jesk, get a qualified mechanic to do it. Both times need to be installed properly and the airbag, particularly, can be very dangerous to fiddle with.