I experienced that same loud noise whilst reversing and breaking, sounds like a cow 'mooing'. To cut a long story short, visited dealership and escalated to VW HQ. Received weekly calls from HQ to see how things were progressing with the dealership, but it wasn't their fault. It's a fault with the break discs/pads which have now been 're-modelled'. VW replaced them free of charge as they admitted there was a design fault with the breaks and a good few people had reported the same. My T-ROC has not made a sound since. I refused to give up and be fobbed off that it was a design feature. Despite this, I love my T-ROC.