Being ****** of data and airtime and charged usage I did not use

So yesterday was the 1st September 2017.... this is the date i receive my R150 airtime which cannot be converted into data might I add therefore I tend to purchase my data monthly. I bought 300MB data at R65 yesterday. This morning i wake up to an sms stating that one of my data bundles has been depleted. When i saw this I was so upset as first of all I use wifi when at home and secondly I was sleeping so how could my airtime of R150 and data of 300MB be diminished. No one else has access to my phone so how is this possible? I then dialed 14302 and saw that everything is ised and my usage is R317!!!! I then took to calling the call centre where the first agent of2 i spoke to was so rude she spoke over me not allowing me to get a word in and insisted I used the data and airtime... a bit unfair dont you think??? The second agent read her scripted notes like a parrot I then asked her to speak to manager she then put me through to a Team Leader who advised that they can only investigate as of the 07.10.2017 as this is when my invoice is generated!!!??? Really Cell C??? I have had countless problems with this bunch. If you are considering taking out a contract with them dont it will be your worst mistake! !!!!