I've gotten the clear from wife to turn a guest bedroom into a theatre room, which I'm really excited about (!), and the room has exhibited some floor bounce in the corner where I'll put my AV gear. this was raised in a builders report, I'll copy it below as it explain the work needing to be done. What type tradie do I hire for pile and bearer system? Is this a capenter type work?

The sub-floor area is reasonably tight beneath the house with some areas not being accessible. The house has been repiled historically, some of which have not been
tided to the bearers, which is recommended. The very front pile as one enters beneath once the baseboard has been removed, is
on the edge of the excavation and is technically undermined as the removed soil is lower than the original footing. The far side of
the house beneath the bedroom, it is recommended that, and additional pile and bearer system be installed to better support that
area of floor that shows bounce.