Billing on Cellphone Insurance

I have a cellphone contract with MTN and are using Paniclemarketing as their third party insurance company. The insurance was billing (duplicate insurance) every month on one tax invoice and the matter was reported to the relevant department and refund was made on the 6th of August 2017 from Paniclemarketing. MTN customer services confirmed to Paniclemarketing with an email stating "Please note duplicate insurance has been cancelled as requested Reference Number: ********** 5". But since then i keep on receiving sms from MTN saying my account is in arrears with R694.79. I called MTN call center now and then the respond i get is there's nothing we can do mama but to escalate the matter. On the 11 September 2017, i called again with ref no 1- ********** 0238 stated that the matter has been escalated to the relevant department and the consultant who assisted me explained to me that they only past credit journal for only one month and not looked in the matter from where it really started . A day after the called i received an sms stating that "your query has been resolved with the very same reference number 1- ********** 0238. This morning i got an sms with a reminder of your account is in arrears with an amount of R694.79. This is so frustrating and thinking of just terminating this contract with them. Kindly assist.