Telkom Poor Service

We subscribed to Telkoms 2TB LTE data deal. At the time we subscribed we were using appox. 400Gigs of data per month as my wife is working from home. We were told that there would be no throttling or reduction in the internet speed. Obviously, fair use can never be applicable given the above scenario. For the first 3 months of the contract duration there were never any problems and we recorded download speeds up to 25MB/s Our happiness were, however, short lived as we started experiencing download speeds dropping to nil from round about 19h00 to midnight every night. I phoned te Telkom Customer Service line to complain about this and was promised that they will investigate. This was months ago. Nothing was done to resolve this problem.