Prado Grande Height Control Rattle

There must be an air compressor, electrically operated, to create pressure for the suspension airbags. Not sure why a towbar fitter would be touching that.

Perhaps he has relocated some of the items in the rear quarter and they now don't have their sound insulation .
Does it go up? if not, he has obviously altered or interfered with the OE parts or the position valves.
Again, can't imagine why he would need to touch it. It isn't to do with the towbar. Might be best to get an opinion from somewhere else as the fitter can give you red herrings and bum steers by speaking to you and therefore hiding what the real situation is. Informed about what the problem is, is preferrable to simply trusting them again to make good.

It should all be tested BEFORE leaving their premises and any shortcomings rectified prior to your pickup of the vehicle.

Turns out due to the install the compresser got a bit to close to a bolt, or should I say a bolt got too close to the compressor. Hence the loud rattle. They fixed it no questions asked. Always good when its something so simple.