I don't know if its a coincidence but I had a new backbox fitted this morning and after picking it up from the garage I noticed the airbag warning stays red and does not go off like before.

Any advice on what the problem could be?

Cheers

 

was the drivers seat further back than when you dropped it off?
could be wiring under seat damaged if the seat was moved by the exhaust fitter

 

That's funny. Mine came on yesterday too but I haven'thad any work done. It has gone off itself after a few drives.