10G data vanished first 4 days of the month

I have a contract 8ta with Telkom with 10G data day time, additional 10G data from 12 to 6am. The 10G data vanished on the 4th day of the month. Purchased additional 5G data at about ,30 am. At about 9,30am the data had also vanished without I been able to use it. Contacted Telkom on the 5th January was given a case ***8. On the 6th received notification that the case was being investigated. I have called Telkom about 10 times, sent 4/5 emails and several SMS to no avail. The response I get is that they tried to call me on three occasions, and could not access me. This is untrue as my phone does not show any missed call and no message was left. The last two days 20th and 21st January I have called them several times. The response from the Call Centre is that they will call me which never happens. Manage to speak to a supervisor by the name of Melissa who guaranteed me that the person investigating the case would call me. It did not happen. I am now in the process of cancelling the contract .They have all my contacts including my email address and yet they made no effort to resolve or address the matter.