How can I close a comments discussion?

Question

I have a user going into an endless comments dicussion... How can I put an end to this comments thread? Thanks.

Comments

Just close the Question saying that question is discussion based.
But if your your website discussion based then there is no way to close comments separately  for a particular question.

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Yes I closed the Question, but this did not prevent this user from commenting.

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did you ever figure this out? I also have a closed question where users keep commenting

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Very odd that Closing a Question still allows comments. That feature should close most activity on the question.