Account cancellation

My name is Khethiwe Mahlangu. ID no ***. On the 31st of May 2022 I went to Chris hani crossing mall to pay my Jet account and my balance was R47.55 I pay all the money ask them to cancel my account for some reasons, they told me to back tomorrow to call RCS company. I do as they told me, the lady who was in charge told me RCS doesn't pick up there's nothing she can do I even tried to call them numerous times with no luck, now they are busy sending me emails and sms and phone calls saying I owe Jet R1262.18 and for what I don't know and the lady who called me said my account is still active yet I left my jet card with the lady who was helping when I asked for the card the next day the told me the card is with the manager and the is on leave. Help me to cancel this account.