Well, I bought the tripod collar for my 70-300L and after 1 week of use the velcro inside chafed itself, which led to not being able to turn the lens around, because that material is so sticky. I sent it to Canon and they sent me a new one, same problem again.
Sorry to hear this problem, Canon won't produce them themselves but buy them from changing manufacturers. For that price and the fact that it isn't included in a €1300 package, you can try sending it back until they give you an acceptable one if you insist other people got a version that doesn't need tampering with.
Personally, I bought a ~$10 Chinese rip-off version of this thing, which (sorry to add insult to injury) is just fine and lets the lens turn if you don't fasten it as far as it goes. The Chinese version doesn't match the lens' color 100% though :-p