It's not a tech issue,so you needn't settle it out with tech.Hack is a way but is a last way.You should consider improving the private friendship if you might be a longterm coopration with them.Uh? It didn't work? Ok,email and phonecall are your powerful weapons. You can CC to their boss,their management repeatedly till they make a promise.Trust me, your skill might be much more than mine,but in this case,It's useless.