Data disappeared

I recently requested that my cell phone contract be cancelled at the end of my contractual agreement. The day after i put in the request, my existing data was depleted completely. The agent i spoke to could not even verify what my data was used on and all they said was i had 100 mb left and i used it up. The previous day i had over 2 GBs of data and all of a sudden after i requested that my contract be stopped after the 24 month period, my data is gone. Now i know i made the right decision not to renew my contract. Will never do business with Cell C again