If the case is new then it will be under warranty,start a rma process and they might just send you the feet.
I've got a 700D and it looks to me like there are rivets through the floor of the case into the foot.
I believe that the rubber on the feet conceals a hole, and that the rivet is inserted from above, through the case floor, into the foot, and then "expanded". I'd need to rip off the rubber foot on my case, and I haven;t got anything handy to peel it off with at the moment...
Mine has threaded screws underneath the rubber feet. If yours is riveted and they had broke then it should be a trivial fix to just put a nut and bolt in its place, or another rivet if you have the tool.
Had the screw just come undone?