3G data purchases

I have used Telkom 3G data via a router and iPad for a number of years. The contracts I bought were for a 25 + 25gig. The 25 gig was daytime up to 2300 and then the other 25 gig was for the period od 2300 to 0500. Obviously the daytime use far exceeds the night use so the night surfer remains largely unused. It lasts for 12 months after purchase. I usually use the night surfer for updates etc to computers and systems and also to FaceTime family in the USA. I noticed my daytime data seemed to rundown quite quickly. On a phone query tonight I was informed by the call centre operator that the times had changed from 2300 - 0500 to 1200 - 0700. Furthermore I was supposidly advised by SMS. I was not informed And have no knowledge of the change. I have paid for a service the was expected at certain times and have purchased more data for daytime use because I feel that Telkom has moved the goal posts mid fame and are de*****ing clients. They no longer offer these contracts and it is a straight data purchase. I have been using data after 2300 expecting it to be off the night surfer bundle whilst it has been reducing my daytime bundle. I find their behavior ********** and dishonest.