Pathetic Service

I have a contract with Cell C and on Sunday 20th September 2015 at 14:23 i received an sms advising that my data bundle had been depleted. As i was at a function and not using the internet on my phone, i did not purchase another data bundle immediately. At 15:34 i received another sms advising that my usage limit of R400 has been reached for the month. I still have free minutes and sms's of my inclusive bundle, it was only the data that had been depleted. I called the customer care last night to find out what the problem is exactly as my usage for the month was under R100 when i last checked. The answer i got was that there was a data usage of over R300 that took place on the 20th September but they cannot tell me what used the data. As mentioned previously I was at a function and did not use ANY Internet on my phone during this time period and my automatic updates are turned off on my phone. I currently cannot make use of any internet applications on my phone besides whatsapp and I was told i need to wait till the 7th of next month to find out what the R300 and something data usage was for. I think this is quite ridiculous.