If I were you I would just send to their MD. if the correct channels are not open then he or she ought to know about that.
I also find direct contact to board level senior management often results in a more rapid and better response than the normal complaint channels via a customer service department.
I've just done this. Alex Carter's email address is in public domain and works!
I think it may be best to him anyway based on the seriousness of the issue.