Re: how many back talk would you take?
I'm not sure about this case, but I would like to relate something from my own experience.
For the last year, I have trained in a style of aikido that is not what I'm used to, and one of the more challenging aspects is that certain techniques look very similar but actually use totally different mechanisms to what I'm used to. It can take me a looooong time to work out how it is they are doing them. I certainly don't mean to argue with anyone about it, but because I have the pre-existing knowledge about other ways that they are done, it can take a while for the new information to penetrate. This is particularly the case when I am working with someone who can't demonstrate an effective technique. On the other hand, my understanding improved much more quickly when sensei let me experience the technique multiple times. Could this be the case here?
On the other hand, if they are actually being argumentative, then it makes me wonder why they are still there.
Either way, Katherine's "classical solution" sounds like a good idea to me.