Line Suspended Due to Billing Error

On the 3rd of July I received an invoice from Telkom with an amount of R1707.04 due on 31st July. On the 14th of July Telkom sent me an sms saying I needed to pay R1226.03. I made payment for the amount received aftery invoice as it was the most recent amount given. I then received an sms on the 7th of August saying I needed to make payment for the R1707.04 to avoid suspension of my services. I immediately called the call center and opened a case, emailed the call center agent a screenshot of my sms received with the different amount and requested that my line please not be suspended as the billing department clearly has an error. To date, I have received no response from Telkom regarding the status of my case but got an email yesterday afternoon that my case was resolved. I called the call centre this morning as my line is still suspended only to be told that the case is closed and I am liable for the charges. It has been 14 days with 5 follow up calls by me on my case and with no feedback from Telkom and now they expect me to pay. I refuse to pay for this until someone has the decency to calle and explain the Telkom billing department mistake and why I am liable for the charges.