Billing issues

I paid the R219 that I was advised to pay on 1/10 After making the payment i received an SMS and a call requesting me to pay R312.83 . I tried explaining the consultant how unhappy I am with the service but it did not help . I paid the 312.83 on the 13/10. I called today because I received an invoice for R750.83 . I'm worried since my debit order date is the 20th that they will deduct the 750.83 that I do not have . I was advised that the payments are not reflecting on their side so I sent an email of the proof of payments to ***. The consultant kept talking about a refund and I explained to her that the R531 was reversed and I paid the correct amount of R219 but I keep getting SMSes and calls for R312.83 so I paid it . I guess they will refund me the R312.83. The service I guess now I know what to expect if something were to happen to my car . I'm so disappointed. The cancellation fee is estimated at 3500 , I wish I was informed about that at sales or upgrade stage then I would have kept my old device .