MTN service and false adveri*****t

worst service provider. false adverti*****t. advertised once off 20 gig when upgrading but no gigs.wrong packages,upgraded to mega talk M with 100 minutes per month extra but no free minutes. duration of contract should be 36 months but they put it on 24 months. all info on voice recording. want to cancel my mtn contract. tried phoning 5 times to resolve the issues but every time an excuse of system is off line and cant assist