Poor/No customer service from Mix Telematics

I'm having an uphill battle with MiX Telematics. When they sign you on they call you 20 times to ensure they secure the sale. I sold my car a month ago and need to change ownership of the vehicle and tracking device as the new owner wants to continue with the services. I have sent numerous emails and all I get is auto reply with a case number. I send them reminders daily with no response, there's no customer service the number on their website only rings. They only do sales and no assistance when needed. There is 0 customer service. I have been with them for 2.5 years and this is the 1st time I'm trying to get ahold of them for assistance. Little did I realise their poor/ No customer service at all. I have been on social media and realised that I'm not the only one facing this issue. Something needs to be done about this.