Just remember... Business Deal from your side. Do it in a professional manner and it may indirectly cause him to work together with you in a more professional manner.
Phone conversations with him are not working so try to avoid those for now.
Emails should work and are something easily reviewed back on in a misunderstanding. Make the issues, ramifications and soluitons very clear. Dont inject any emotional points. Use "I" statements more than "you" statements.
