Appalling service delivery

I have received bad service from Cartrack . I called in for a device repairer and the agent I spoke to said that I won’t have to pay anything for that service, however couple of days post the repairs I have received countless calls for an unpaid repairs fee. I made a call to your client service to ask about a repair of my device and I enquired if there will be a payment for it and the person I spoke to highlighted that there was not payment due on my end. I therefore advised the repair to be made. I asked the agent countless times and it was confirmed that I won’t be making any payments. Now I am being harassed by different people ordering to make the payment. Since all call are recorded, I asked for the recording to prove that I did ask and the agent told me that I am not supposed to pay. They sent me an email to say that they’ll investigate then now my account is debited without the outcome of the investigation. The service I’ve received is appalling.