Disappearing data, request for investigation and only excuses given

I have a contract with Telkom for LTE and contacted them on 07 October via Facebook regarding the fact that my data had been used up suspiciously fast, particularly since our mobile devices measure wifi data usage and only accounted for approximately 6gb of usage within the specified period where our contract is for 20gb + 20gb night surfer. Telkom requested my account detail for an investigation, which I provided. I checked later and saw that my message had not even been read, let alone an investigation done. I queried this again with them and was told to ensure security on my network before they would proceed. I responded to state that my network IS secured and that this was a poor excuse for non-provision of service. I have yet to receive any response. Since it seems that they won't investigate or at least provide an explanation, I can only assume that Telkom, like most of the other mobile network devices in South Africa, has joined the bandwagon of *****ing data and airtime. I am extremely unimpressed, especially considering the exorbitant amount paid for data and only having it last for 6 days!