Bad Customer Service. False invoices.

I've had the telkom contact for over a year now, I wanted to cancel it because of the bad service, they didn't give me an option for that instead they gave me downgrading options which is not fair, long story short I get my invoices via email for what I must pay for the current month (August invoice R402 end of August, September invoice R4518 end of September) but now my lines are suspended because they say im owing the R4518 which they said they'll debit end of September... I just don't understand now they are saying I was supposed to pay it end of August but they never told me that, Telkom is bad even their consultant Neo who refused to give me her name and I got it from another consultant was so rude. We pay what we are told to pay, when we are supposed to pay it but still our lines get suspended.