I am extremely frustrated with Vodacom’s service

I am extremely frustrated with Vodacom’s service. I received a letter of demand giving me 21 days to settle my account, and I have made multiple attempts to contact them to arrange payment, but no one has responded. Previously, I was told my account was fully paid up, only for Vodacom to later claim I still owed money. This inconsistency is unacceptable. I am trying to resolve and close this account in good faith, yet Vodacom is unresponsive. Their lack of communication is delaying resolution and causing unnecessary stress. I urgently request assistance to finalise this matter.