I think eBay was wrong to remove only the comment, but leave the neg.
This might have been appropriate if you were complaining about profanity, but in your case I think the whole feedback qualified for removal.
One of eBay's policies on feedback stated that buyers are not allowed to leave negative feedback because a seller refused to do something that eBay does not require them to do. In your case, you are a private seller with a no returns policy. Your buyer should not have left negative feedback becuase you refused a change or mind return request.
Unfortunately my link to where this was stated is out of date, and I don't have time to search for it now. Try to find it before contacting eBay. Scroll down to the foot of the page, and click on "contact us". Then in the search field try searching for rules on feedback and feedback removal. You can use the same link to contact eBay customer support.
