Telkom Mobile Billing Issue

I have been trying to contact Telkom mobile customer care for the past 30 minutes + with no answer. I cancelled my Telkom Mobile contract at the beginning of August and my last date that I had data was the 02-09-2018. On the 03-09-2018 I received a phone call telling me that my service was cancelled, my usual bill was R705, but today I received an invoice that stated I will have to pay R654.56 at the end of the month for two days worth of data. I did not even use 2GB of the 100GB of data available. This is unacceptable. I cannot get into contact with Telkom mobile as no one answers the phones and no email addresses that I have tried actually works.