At any time, the buyer who wrote the review has the ability to change their review and edit their response. You as the seller, can also go back and edit your response to the buyer. Once your response is edited and submitted, the buyer will be notified through email. When the buyer edits their review, you will also be notified of the change.
In some cases, the review and response will be closed by BizX as to not allow any further changes. This could be for a few reasons including inappropriate content, or continuous and unnecessary back and forth of messages.