UNUSED DATA NOT TRANSFERRED TO NEXT MONTH

Good day I have a data contract with Cell C. I recently made an enquiry on my data account to find out how much data I had available. I was told what amount of data I had available I queried the amount. I was told that data left over from the previous month could not be transferred to the new month. I paid for that data. I am sure that Cell Service provides are now required by law to carry over data.