Vodacom not responding

My husband finished paying our cellphone contract in May 2021 and he even received a statement showing 0.00. Month this he picked that he owes Vodacom R1500 via ITC. Who communicated this to him ? And now he keeps sending emails and trying to call you number that never goes through. We are so disappointed buy this, what is the purpose for us to send emails in which you guys never respond. Your incompetency negatively affecting his credit