It is unfortunate that teams have not been able to aquire quantities of the competition-like ball... but, there is a positive lesson here... (Aidan ducks)... in the real world of engineering, the material/object that a machine has to be built to interface with is often not available.... and when it is, specs on the object change mid/post design all the time.
The extreme example of this is evidenced in our friends Spirit and Opportunity. They had to be designed without actual Mars rocks, actual Mars gravity, actual Mars dust... etc.
So - amid your frustration - be sure and teach your team that this is not an insurmountable disaster - but a lesson in real-world engineering.
Aidan (still ducking behind desk...)