Data not carried over

I receive 2G Data per month. On 28 October 2015 at 12:24 I received a SMS that I have 1.2G data left. I followed instructions on *111# and confirmed that I had many Data left. The following month, which was 3 days later, nothing was carried over and I started with my 2G again. I called and was informed that I used 1G up in one afternoon and has no data left, did nothing than normal.<br> On 30 November 2015 at 12:24, last day of the month, I received a SMS that I have 817MB data left and confirmed it at *111#. Again my data was not carried over and again I was informed that I used all my data. Now it seems I am using all my data at the last day of every month and I don't do anything abnormal.<br>