Billed for a settled account

I have an account, which in May I decided to settle and requested cashier assisting to close the account. He gave me some story that they are unable to close accounts at the store. I left cause I was in a hurry. A couple of months down the line been getting messages that I owe Jet. On 05 September I decided to visit store and find out where is the balance coming from. Consultant contacted helpdesk, I explained my store and requested that they give me list of good purchase that make me owe a balance with them.

The guy on the other side confirmed that account was settled in May and was left with zero balance, however there is a cellphone insurance that collects R50 on monthly basis and I charged service feed of R30 monthly. I was very angry and frustrated because the insurance was cancelled years back. That means Jet has been billing me all these year for insurance cancelled years back.

I explained to Akhona from call centre. Who promised to speak to his manager and get this balance removed and confirm with insurance company and have me refunded. He promised to send me a mail on Monday the following day conforming what we discussed and also give me a call. This did not happen. No mail or call receive again I am getting sms's that require me to make payments.

I am very disappointed at the store the service is just parthetic, I just need help