It is Impossible to get hold of anybody at Mix Telematics

Recently upgraded the tracking unit in my vehicle. Subsequently the monthly charges changed and I was promised by the consultant my monthly fee would be less. My monthly fee is now more than double as Mix Telematics is charging me for two vehicles instead of the one (and only) vehicle registered on their system. I’ve repeatedly phoned their debtors department and logged notifications via their e-mail channels. Nobody responds to these queries? What must one do to get hold of somebody at MixTelematics? I’ve been a customer for more than 5 years. This type is service and lack of communication is appalling.