Who does my wife pay her insurance excess to?

My wife's car was in a prang and it's currently in the bodyshop. Should be ready by Friday. I know she has to pay a £500 excess fee, but is the excess normally paid direct to the garage/body shop on collection, or to the insurance company?

I'm at work now so can't easily look at the insurance schedule/paperwork until later, so just wondered if anyone knew what the norm was as I'll have to arrange a transfer to her if the garage will need paying on collection. Insurance company is Aviva if that helps.

Thanks!