I thought your wheels were sponsored? Just let Rota know and I'm sure they will send you a new one.

My personal thought on this is that you will have a hard time trying to prove your case. You only have the recieipt to show for the car wash, but that is no different than "hear say". Anything could have happened during those 2 days before returning to talk to a manager. That's why they are taking that stand... You should have taken pictures of it (date stamped) or with that day's newspaper on the picture. Pictures of the car and the car wash, and whatever pictures that could have been used to prove your case. You could have also called a police officer (non 911 call) to have a damage report filed. That would definitely have given you the upper hand.

Get your wheel replaced with Rota.