Abnormal data consumption !!!!!

On the 6th of October 2019, I observed high data usage on my cell C cell numbers. I then purchase 2g any data around 8 am. The high data usage continues and out of concern! I close any apps running! I run a simple test where I opened the facebook app for one minute @ 11:15 and check my balance. from the test, almost 100 MB was used in 1 minute. At 11:16, I ran the FNB banking app for the same period, and almost 60 MB was used. It called Cell C customer care 140 and raised the complain whereby i was issued with ref number: *** and I have not received any feedback from Cell C