Accident with bus - what's the procedure?

[Rabbo]

The missus was overtaking a stationary bus (stopped at bus stop) which then appeared to indicate and immediately pull out whilst she was alongside, taking most of the paint off the side of her beloved Z4. The bus didn't stop and she (bless) didn't get the registration, nor were there any witnesses. As far as I know, if the bus wasn't indicating to pull out when she overtook, she technically won't be liable - correct? Not sure whether to call the bus company or insurers...