Bad service from Cell C

<p>I have a cell phone contract from Cell C direct, late last year I believe I was being over billed so I called their customer careline to get an explanation regarding my bill but they failed to explain it to me, on December 2nd 2015 my bill was about R3500 and mind you I dont know how it got there but however I paid them R1900, in January 2016 around the 25th they called me telling me that my bill was about R4500 yet I had not used their contract sim cards, I asked them how come because I have not been using their sim cards and i paid them R1900 in December, they told me that the payment doesn't show on their system however they will investigate and get back to me but they haven't. I have emailed them but they never respond to my mails.</p>