Blacklisting the phone after selling

Dear Vodacom, Good day, I bought a phone from gumtree and i paid X amount of money and i still owe him 1000 rands towards the phone but i failed to pay in time , so the guy lodging complaint and he went to vodacom to blacklist the phone, i would like seek help from vodacom is this possible as i didnt deny paying him and also i have payment proof as i paid most of the money, can someone black list the phone even though they sold it? thanks