You can try and have the negative feedback removed if you think you have a good case, however by the sounds of what you have written the member probably felt that they had good cause to leave it.
Unfortunately this is just one of the many issues that can seriously hurt you when doing drop shipping. Some providers are better than others when it comes to communication, but no matter who you deal with, drop shipping has its pitfalls!
Don't worry, you won't be the first to fall into that one, and you sure won't be the last!