Cell C for them-self

I bought R300 airtime to buy a data bundle. I found that I only had R293 left, so on Monday eveneing I bought a further R80. Yesterday I tried to buy a data bundle and found all my data and airtime was missing. I was fuming and phoned customer service who told me that I ran out of data so my airtime R373 was used for data and I had "stuff running in the background." All apps were closed except whatsapp, which I have a shout out bundle for. I use my phone in the same way with the same settings every day, yet suddenly "stuff running in the background" is depleting my data. I also received NO notifications whatsoever that Cell C was going to use my airtime as data, and that my bundles was depleted as per ICASA regulation. I want mt R373 back. Either cell C billing system is not working, or Cell C staff is *****ing airtime/data.