Billed R3400 for 1gig

On the 26th of November 2017 I purchased 1 gig on my mtn self service and they charged me R3400.00 and suspended my line immediately. When I called in to enquirer I was informed that it was an error and my line was reinstated however my account will be sorted out on the 7th December 2017 , the 7th came and went . I’ve been following up when I receive a sms advising that my query has been resolved . When I called again yesterday and requested to be transferred to the billing department I was informed that they do not have a phone but will be sent an email. I asked to speak to a manager who had no empathy for my situation and could careless if I cancel my contract or not . I guess I’m yet another number at mtn and made feel that 15 years plus client can change service provider because mtn was unable to resolve their own mess. So no one really cares about clients at mtn period.