Cell C not resolving issue...

Last year I contacted the call centre regarding how my airtime was running out, a few cents would be deducted a number of times during the day without me doing anything on the phone. I checked to make sure I wasn't subscribed to anything, no apps (besides whatsapp) running. The call centre pulled a report and basically told me that whatsapp was causing this. So this carried on for a few months. A couple of weeks ago I bought the cell c whats app bundle - you get 1GB data to use for whatsapp...a day later I see its still using my airtime. I called the call centre and the lady was rude, refusing to listen to what I was saying n cut the call. I called a day or so later and asked them to check, they logged a query, then sent a message saying it was resolved, I called the call centre and was told that I was downloading videos, I did not download any videos, she then said they will call me back and nothing yet...wth is going on, why is whatsapp (the only app running on my phone) still using my airtime? I am seriously considering changing networks over this if you cant resolve this and refund me all of the airtime that has been disappearing (excl calls and sms's) - ref ***