Telkom contract data disappearing

In August 2017 I took a monthly (10GB day plus 10GB night) data contract with Telkom. All was good till the month of March 2018. Within the first 3 days of the month all the daytime 10GB data was gone. I called Telkom on the 4th of March to inquire about the data and I was told that the data was consumed in the following manner 5GB on the 1st at midnight, 2,5GB on the 2nd at midnight and the last 2,5GB on the 3rd also at midnight. I was asked if I had anything that automatically updates connected and my response was, no. to which I mentioned to the call centre agent that, it was impossible for 5GB to be used in one minute and that if the data was consumed at midnight, then it should have consumed the nighttime data. He then changed the story to say that it seems that their system did not record the data usage log and that he will log the query with the back office for an investigation (ref.no.: ********** 3). All this happened with no device connected to the router. He then told me that their turnaround time is 72 working hour (which on its own is ridiculous), that is nine working days. This 72 hrs lapsed yesterday without any feedback, that is despite me calling daily this week, with call centre agents promising that "the back office" will call me. All I need is to be allocated the data I am paying for and if they claim that I used the data, I need them to provide me with the detailed data usage log; showing which device was connected. In the past they were able to provide a usage log as well as the type of device which was connected.