yes, I agree. dumb move on his part.
request a refund and send it back (after recieving the refund)
quickest and least complicated
or... have a tech repair the knob (or do it yourself if you can) and ask a refund for the damages (send copy of invoice of repairs) - this is more complicated and will require coöperation and understanding of the seller.
best way to pack is bubblewrap box then more bubblewrap or something that can buffer heavy blows and then a sturdy outside box.
I've had heavy mixers and midi controllers (faders !
) arrive here in just one thin layer of cardboard
some ppl. don't have any idea what will happen to a package
Royal Mail is worst IME, Dutch, German, French and Spanish mail and couriers are mostly very good, but Royal Mail is doing soccer or rugby games with heavy well packed gear. Wankers.