The sim duty is true unfortunetly
I have been called off standby twice to do a sim spare body duty, I thought I was getting paid for it and I didnt, the 2nd time I was called I asked crewing why I was not getting paid and they gave some bull!!!! answer and hung up before I had chance to reply.
spoken to BRK about it and was told the would call back with an answer and they didnt, called again and was told they would call back and they didnt!
next time I get called I will be asking for paying for it or I wont be going.