Light won't come off...diagnostic tests show- ignition circuit, window bag, passenger side.... is the wiring in the roof or side pillar??

Open the boot and inside the cubbyhole hole on the passenger side, by the strut turret, there's a yellow connector split it and reconnect... link the diagnostic kit up and see if its gone... clear the faults if you can and come back to us

OP have you tried this guide?

https://www.fiatforum.com/stilo-guides/72482-airbag-failure-warnings.html

Yey, Thanks it worked...I am one happy lady