I don't think they can be bothered with UK customers any more, returns must be much more difficult/costly for them to process. Couple that with them being a box shifting volume seller means it might be less lucrative when inadequately packaged cheaper items end up damaged. When I returned a bass to them two years ago it was all wrapped up much faster than this.
Would have been a better idea all round to ask you to make a video of the damage making sure the serial number was visible then just offer a decent chunk of money off.