Billed for cancelled service - Mix refuses to credit account

On 11/06/2020 I requested tracking to be cancelled on my old vehicle and new tracking added on my new vehicle; Mix Telematics have billed me for the whole of July for both vehicles and refuse to credit my account for the cancelled vehicle as, according to the lady that called me today, their billing run already took place so I must pay. This despite me only receiving the July months invoice / statement on 2 July (two weeks after the event). Mix telematics have informed me this is policy and they do not give credits. The value is small and this complaint is about the principle that should be logged with the consumer council for Mix Telematics collecting money for a service already cancelled and refusing a credit. If Mix Telematics collects and extra R30, R40 or R50 for vehicles where the tracking has been cancelled, they are enriching themselves and need to be exposed. This is theft. I am so disappointed it their conduct and ethics. Their books should be audited for cancellations where they have continued to debit customers accounts after the cancellation date.