Not willing to provide basic information

My phone broke a month ago. After assessment, the repair company told me it had been blacklisted. As it was no longer under guarantee, the retailer required me to confirm that it was blacklisted. They sent me to Vodacom, who refused to assist. I have heard from a number of people this has happened to, and they all got information about blacklisting from their mobile service provider. Why is Vodacom different? Why won't you provide information? This is crazy.