Considering the solidity of Rigol's instrument casings, your scope must have taken a real good blow to look like this. Did you test it to still work within specs? If DHL offers to compenste you for the damage, I'ld probably rather take a full refund than attempting a repair -- you never know if the hit left hidden flaws that may manifest themselves at a later time.
If your only option is to fix the instrument, I'ld contact Rigol's subsidary in charge for your area and ask a quote for the spare. I assume the casing back is identical with the DS1000Z-E, so you can take the spare part numbers
from this service manual. If they cannot help you, you're probably out of luck and may look at glueing the crack of the existing casing (PMMA adhesive works best on ABS, i.e. "Stabilit Express" or the like) and fix the flap-out feet.
They are especially crappy on the DS1000Z and I'm waiting for the plastic prongs to snap on mine everytime I flap them out. When this happens, there's no way I'ld install the same crap (spares) again but I'ld rather drill through the feet from side to side slightly smaller than the diameter of the plastic prongs and push a steel shaft through that I'll beef up at the ends with some brass tubing to match the original size. This way, the feet will last forever.
Good luck with your scope, whichever way the road may turn...
PS. Fungus beat me to that, but what the heck, I'll post anyway