Picktree Car and Commercial

I was sold a car by Picktree 11 months ago for £3000 . Took it for its first MOT and the car was condemned due to corrosion on the chassis. Took it to a repair specialist who advised the rust is so bad its not safe to drive and it had built up over years and he could not reapir it. I reached out to picktree to try and resolve this and they refused to offer any help are support.