out of data billing on capped contract

In Dec 2015 my ipad's Internet stopped working, I left it thinking it was because I was out of data (I have a capped account for 2gb). When we got back from holiday in Jan I still had no Internet. I visited an mtn branch and it was explained to me that I was out of data...he showed me that I had used the 2gb where after my data is cut off completely. So during Jan I couldn't use my ipads Internet AT ALL because I was out of data and had to wait until end Jan for new data...<br> <br> Now I get a bill for more than R700 for switch pack data billing which is out of data calls during Jan. Can someone please explain how that is even possible if I had absolutely no Internet on my ipad for the whole of Jan and if I have a capped account. I know their answer is now going to be that I don't have a capped account, so let me tell you upfront, that is a bull*** excuse cause I've always had capped and my Internet was definitely cut off when reaching 2gb.<br> <br> Mtn has long been given me endless problems but thus is absolutely unacceptable . I will not pay any out of data calls.